R C-R

I think you might be talking about the align top, align center, align bottom, Justify vertically context menu item when you have a Frame text object selected. That will not do what you want.

If you also have APhoto you could use that!

There are free tools, such as XnViewMP (and its sibling XnConvert) that will do it.

c'est simple, quand dans Affinity Photo 2 je fais une sélection d'une zone avec la baguette magique, je voudrais convertir cette sélection en coube vectorielle (comme c'est possible de faire dans photoshop).

Doesn't thomas's reply answer your question? (i.e. You cannot convert/trace a selection/shape to a vector curve in Affinity.) Until this feature is added to Affinity, (if it ever is!) you need to use a third party app.

To me, it is both logical & necessary to avoid confusion over what might or might not overflow the frame & why it might not all be visible, as I explained above. Plus, if the frame was not visible, neither would be its bounding box handles for rotating or resizing it. 
So to me, it is a basic UI feature, one that all objects should display whenever selected.

My most likely explanation for what happened is I might have renamed a parent folder while the Affinity file was still open. Which of course would have messed up the path. I didn't think about this until after I made this post but it occurred to me that I did need to rename some folders and likely forgot to close every single file down first. Ever since then everything has been working great in Affinity so I'm not so worried about it at all at this point.

To me, it is both logical & necessary to avoid confusion over what might or might not overflow the frame & why it might not all be visible, as I explained above. Plus, if the frame was not visible, neither would be its bounding box handles for rotating or resizing it. 
So to me, it is a basic UI feature, one that all objects should display whenever selected.

It is a local website.

A screenshot of your full Application window will help.
please consider that you can configure which tools are visible in the tools panel, and you may have deleted the tools and can re-activate them.
 
https://affinity.help/photo2/en-US.lproj/pages/Workspace/interface.html

If your Text Frames exist as objects inherited from a Master Page, just create a Layer layer on the Master Page, change its layer properties to have a White color, and put the Text Frame(s) in that Layer. Then they will have a white outline on all pages.
And to change them all back to Blue (or whatever you want) just edit the Layer properties on the Master Page (or on a document page using Edit Linked).
Note that Text Frames are objects, and the bounding box of an object that is selected is always displayed even in Preview Mode. So to me it is logical that the bounding box is visible even while typing in the frame, as the frame is selected at that point.

Try this:
Create a new document with 1 master. (It doesn't matter how many document pages it has but to keep things simple limit it to 2 pages.) Add to it an Art text object containing the text "Master A." Select Master A in the Pages panel. (It should have a blue, not grey, border.) Click on the Duplicate Selected Master button in the Pages panel. Double-click on the master you just made to open it. (It should then have a grey, not blue border.) In the document view change the art text to "Master B." Go back to Master A by double-clicking on it in the Pages panel. (It should have a grey, not blue border.) Does its art text object still say "Master A"? If not, please consider posting a screenshot showing the Pages panel with both masters visible in it.

In Preview mode, I click outside the text frame when I want to check my page clearly. When I'm actively typing in  the text frame, I don't bother if its bounding box is visible. 

@R C-R Sorry, Time Machine.

From Help on Windows:

 

It's the same! (With a right click.)

... but as has been said many times, due to the fact that the Distributing/Space of objects is also set in the same dialog, it is necessary to first select the type of operation (that is why it is placed first in the dialog), and only then the parameters of this operation (that is why the parameters are placed second and made available only after selecting the type of operation). 

1. Select both objects
2. ALT+Click on the Rectangle - This sets it as the key object and it will not move
3. Layer > Alignment > Align Centre
Note: If you actually wanted the Ellipse inside the Rectangle then, also, do...

4. Layer > Alignment > Align Middle
Your post was a little unclear if that was what you actually wanted

They do ask the customers the right questions!
Serif provides all information about found and possibly fixed bugs in this forum, including a powerful search function.
But only a few users use it.
The majority of users waste their time writing lengthy, or more or less meaningless, error messages instead of spending a few minutes searching or analyzing the FAQ sections.

you can provide this info proactively with your very first post, saving the time it takes until someone would ask you expecting 1:1 support interaction with staff, solving a problem that has already been discussed in this very forum including solutions or workarounds,
using that passive-aggressive entitled tone over a 100 bucks one time purchase is 'interesting' coming from a professional.
I think it's quite possible you already wasted more time here ranting (without appearing too eager to solve your presumed problem)
than what your AP license cost you.

Consider how many different Nvidia processor & driver combinations there are in use globally, & how often drivers get updated. The number is probably well over a hundred possibilities they would have to test, & they probably would still miss a few.

There have been many posts made by the staff about problems with certain Nvidia processors and/or drivers for them, suggestions about either disabling hardware acceleration or trying different drivers, including links to where to find them.
So I am not sure what more you expect them to do than that.

That's the point! If people want help regarding crashes or lagging they are unlikely to look at a post which appears to be about Serif's staffing policies! 😉

There have been many posts made by the staff about problems with certain Nvidia processors and/or drivers for them, suggestions about either disabling hardware acceleration or trying different drivers, including links to where to find them.
So I am not sure what more you expect them to do than that.

Consider how many different Nvidia processor & driver combinations there are in use globally, & how often drivers get updated. The number is probably well over a hundred possibilities they would have to test, & they probably would still miss a few.