Cutting masked area gives inconsistent results

[bwbecker]

I'm working on adjusting colours on a large map with many individual details.  When I create a new layer with a mask, it seems there are remnants of the image from outside the mask.  Let me explain.

I use "Select Sampled Colour..." to select the colour I'm interested in changing.  On the far left is an area outside the image.  There are two selected areas that I want to change.

I then do a Cut.  I'm expecting to paste that as a new layer:

Note that the tannish areas (that were not selected) have been affected.  Furthermore, the selected area in the centre of the above screencap appears different from the selected area on the right.

I now do the paste and then hide the base layer (uncheck it in the Layer panel):

Notice that the two areas I originally selected appear different.  Also, there are remnants of the base image outside the selected area.  I now add a new recolour adjustment layer as a child of the layer I just created:

Notice that once again the two areas I originally selected are treated differently and the spaces I didn't select are also affected.

Here's the layer panel, just to be clear:

Can anyone explain to me why the selected areas are being treated differently and why parts of the base image are sort of there and sort of not there after doing the cut?

Thanks,

Byron

PS:  This is Affinity Designer 1.7.1 running on a MacBook Pro under Mojave (10.14.5).

 

[firstdefence]

Note: If you have made a selection and you are happy with it, that selection can be saved as a spare channel enabling you to reload it later on, this aids consistent selection patterns.

It's likely the coloured pixels not picked up are "too" transparent to be selected as a colour or something akin to that. Have you tried using the flood Select Tool   and unchecking the contiguous option on the tools context bar, this will select all area's of the colour you are clicking on not just adjacent pixels, click and hold and then drag the cursor to increase the selection to see if this makes a better selection, as you drag the Tolerance percentage will increase until you have what you want selected, if you get a clean selection go to Select > Save Selection > As Spare Channel, when you want to reload the selection just go to the Channel Panel and right click on the Spare channel icon and load to pixel selection. You can also save as a file if you have multiple image and can the same selection into each file.

Maybe load a sample of the area you show so we can look at it. 

[bwbecker]

Thanks for the reply, firstdefence.  However, my problem is not with the selection.  The selection shown in the first image is close enough to what I wanted (the two orangish-tan areas with the "ants" running around them).  My question starts with the second image, after I've done a cut (as in "cut 'n paste") of the selected area.  It appears that my cut affected pixels outside of the selected area.

I don't believe there are any areas of my image with an opacity less than 100%.