qaman333

The same happens sporadically to me while having only one image open ( I rarely open more than one image at the same time) (AP 1.10.1, macMini  10.13.6). My usual custom setting is a crop ratio 1:1.

Maybe  i need a cup of coffee too, or you are writing in a more crypto style than me? 
I geuess you mean the view of the brush-"presets"? You just want to show its small "symbol" not the line-preview for displaying more brushes in a role? 
AFAIK there is no way to personalize this. BTW the whole preset system is suboptimal. Do not trying anything of the following - it also does not exit yet:
 
There is:
- no way to change / order / move a style (just rename, but no apha-order...)
- no way to call a preset DIRECT from an adjustment-layer-box
- no gradient-presets (avaiable on all „gradient-stationes“ directly)
- no way to „preset“ a filter, no filter-gallery (showing all my presets, which collapse when mouseover)
- and there are no subcategories/folder for any preset-system
- there is no „global“ preset-manager which allows subcategories, batch rename, batch move, batch delete… as a central point for organizing ALL stuff in all preset-systemes and also to use as fire-up/launch-station.
 
(Just the macro-preset-system is a little bit as it should. I can drag and drop between categories, reorder inside a categorie and rename…
But here the look is not overview-friendly: Categories are smaller than single presets and the color category/content to near by eachother… and also: no subcategories... But even with this lacks, it is so far the best of all preset-systems in AP.
 
Apropos „Macro“. In the musician / DAW-world we know container as host for different FX (filters). For example: I often use a combination of 2 filters and 3 adjustments. So i would put them into a container (group). On the first level of this group i get a „box“ with the parameter i have designed for tweaking. (Similar to design a parameter for a macro).The difference to a macro would be: A macro-tweak-interface get lost after apply. But this „container (group)“ would stay as long i wished and i could later readjust as i want (of course it's not compatible with destructive filters).
And i could create and later edit this container in a much easier way than recording/edit a macro. 
 
For brushes: I would love to have an option: Hold current brush settings (size, hardness...), just change the texture! So i could trash lot of redundancy brushes, which would make the library more overview/faster. Also the big preview for brushes could be more compact, instead show more brushes in a row (like for styles) - but it would be nice to see just a temporarily dedicated bigger overview when mouseover a brush in the selection-panel (and IF this big-view-feature is checked).
 

I completely agree.  The brush studio seems flawed in its implementation -- at least to Procreate where you can much more easily see what brush you are using.
As noted when using Brush Studio
1. Select Brush -- it is highlighted
2. Change any setting such size -- it is no longer highlighted
3. Return settings to original -- still does not highlight
4. Brush Name Not Shown -- it also hard to know since you cannot remember a name, unless, as noted, you go and fuss with the advanced dialogs for the brush.  Hovering will show the name, but as I am using a Wacom Cintiq this is agonizing hard to do.
I find this exceedingly frustrating as I am doing digital art.  Makes me want to look at other programs to see if they are better suited to digital art workflows.  My hope with Affinity is a single product between macOS and iOS ... but even something as "trivial" as this is a huge amount of friction to me -- especially as is only one of 3 studios I really care about:  1) brushes, 2) layers, 3) colors.

The WHOLE brush-concept is suboptimal. The functionality is almost great, but all aspects of access and the handling is... could be much more better
 
1. View of brushes
With hundreds of brushes in dozens of categories... you will become some problems to find which you want. The only possible preview-view is this stroke-view. This view is complete useless if you search for eg. a texture, or if the size is set to a small or extra-big value... There is absolute no option to show/order the brush just as big quader-view, showing the "texture", sort by size, sort by name.. BTW: when doing any other action, and going back to brush-panel... the highlight is disappeared, so what brush im currently use???
2. Fast access to standard or similar brushes overall
However in which category i am, which tool i use...  There a lot of situations i need a standard-brush during the situation i use other ones. Same by changing the tool. Its nice that last brsuh for this tool is remembered... in maybe 60% thats a good choice.  But as said often i need a standard-one. The way to panal-brush, hamburger to simple, choose one is very very long windowed, the way back is even more complicated, if do not remember, which category, which item...
The solution: Right-click: Besides other context-options, each brush-like-tool offers a right-context and here are in the first divide-area some entries like this "use standard 1,2,3..."  (i have defined 5 standard brushes); "go to favorite" (here i have maybe 7 favorite brushes... in maybe different categorys, the brsuh-panel will automatically react to this); and "go back"...here are my last 5 brushes (except the standard ones). 
Another right-menu- (better context-bar) should be: "Use current size" and "do not use tool"  Each brush has its own size, and some ones special tools.This is often a big advantage, but often not. If i just searching for TEMPORALLY POSSIBLE brush... i almost want the candidates in a equal chosen size, with same opacity... and of course i do not want wet edges or another tool, when just searhing for this job. This checkboxes, will narcotic the special UNIQUE brush-settings and call them in the most familiar way as the current one. This is only valid as long the check is active!
3. Edit a brush TEMPORALLY or as automic "OVER-WRITTEN"
There is absolutely no way to temporally change a brush, when using the brush panel. ALL settings there will immediately "stored" without asking. But in 90% i just want this changes just temporally...  There should be a "Save/Overwrite" button, if i want this changes PERMANENTLY,  otherwise all done settings are just temporally, just for this current job and only valid as soon i change to another brush! If i want this settings PERMANENT., i have several options: Overwrite, Save as (= duplicate+++, below the original), Save as in category....  save as VARIATION (later more)
As said before: A context-right for brush-tools would be great. Here could also be the entry "open further settings". This will popup  the brsuh-setting-panel  from above, but directly here. And this panel gets automatically closed if the mouse get outside the panel. EXCEPT: i hit the button: Stay in front, or so. Otherwise its a one or maybe 3 edit window, as long visible as the mouse is inside. 
As said before, all settings here are just temporally, if i change the brush, all is forgotten, except i EXPLICIT save as/overwrite... 
4. Do we need so much brushes? The Power of VARIATIONS!
What is a brush? Except the standard ones, a brush is just a HOLDER of a single- or several images... with special settings, how to repeat this images. I would say all "brushes" which use the same image(s) are one brush, but different variotions. Well the settings can be so extrem different, i would not say its a family, even if the definition above is valid. But for lot of brushes we could put them together as just "variation". Grunge-Edgy-brushes for example. We need this brushes as top, left, above, right... edges in maybe different sizes... Or texture brushes with the same images in different sizes/rotations/opacity/flow...This will grow up our librarys, lot of SAME brushes will appear as single-ones. With VARIATIONS that would be much more easy, faster, smarter... 
If i right-click of on a VARITION-brush i get all its "Variations" (size, rotation, flow, opacity... dynamics... and combinings)... as one-click-selection! This would, save lot of same brsuhes with just different soizes...rotations... organize all brushes in a significant better, very fast and really smart way. A piano-sound keeps a piano sound, even with different play-wise and lot of FX. Well, if i do a lot work, it maybe can sound like a contrabass... but why not use the contrabass as first element???? And if my piano-fx sounds like a saxophon... i will take this sample as new "parent" for new variations... The "family-idea" keeps under all circumtances the same. 
And yeah, normaly 0-1 sets the opacity for a brush... if i option, why not use this numbers instead for my dedicated, more precise VARIATIONS???? (i can use normal behavior or say: for this BRUSH use the fisrt 10 variations...)
5. Creating new brushes/behaviors/dynamics...
Why can i not rightclick a layer and say "create new brush from it"?  This longwindow via save and search in the brush dialog... ist sooooo unsmart!
Why not "repeating" part of the image but in front and end there will be take other parts of the images, like an audio- sample, its repeats just only the "middle" but will fade in/out... 
Why not using special-keys for special dynamics? With shift all dynamics will pressured and with command all dynamics will multiply by 2..... or control will change the size, even if sizedynamic = zero.... and so on...
6. Presets
Well ALL of the AP-Preset-SystemS (yes plural) in AP lacks of lot things. Some are rename, but not moveable, some one  can organzied inside a category, but the categorys not moved... and so on... It seems, dozens of single-people, without any ideas of concept and "anticipate user wishes; unslave them from lot of long-windowed" could try their luck! ALL this systems are inconsistent, each other, and long-windowed and i would say Semi-semi-semi-professionell. My 7 years old daughter would this better "concept", cause she knows, its better to have ALL colored pencils in separate boxes , not in the whole flat, room, garden... AND she knows sometimes its better to reorganize ALL pencils to project-ones... But even than, after each projekt, she is going back to her normally order... she likes most lexibility WITH basic-structure and she is very, very lazy... maybe thats the reason, she does not like to do things twice or long-windowed, or over-complicated... she is FLEXIBLE-PRAGMATIC, before doing anything, lets get an overview... is this the best way? who says???? what would be, if...!!!