I work on the missing part of the mask on the right and what I have just corrected on the left comes back.
I Save Current Mask again.
I go back to making the correction to the left of my wife’s head and the fault to the right comes back again.
The only reason I am doing Save Current Mask is because I somehow crashed the app (mea culpa) and felt this was the way to protect myself at each step. Save Current Mask does not ask for 'permission to over write'. Should it?
Save Current Mask does something other than what you are thinking it does as it does not offer any protection against mishaps. The feature is something akin to the Store and Recall buttons on some calculators -- it makes a temporary copy of the current mask so you can combine it later in the masking process with some other mask.
I am on vacation and don't have time right now to investigate, but I will take a look when I get back around 4/25.
To save your work, just close the current transformation and save a workspace script -- this will save everything including all transformations and masks. To restore, just reload the workspace script.
Or, just save the final image along with a script file and you can open the script file and resume working on the mask.
The first time you use a tool you get the defaults. Subsequently, they revert to their last settings when you pick them. In this case you were in subtract mode so the tool removed the selected color range. Some tools apply immediately since they just require slider or other controls to determine their settings while other tools like the freehand lasso, flood fill, etc require you to draw on the input image so they do not apply immediately. Color Range is of the first type which I think led to your not expecting the immediate result.
So I caused my error by not moving into Add mode before changing to the Color Range?
I'll have another crack after lunch (GMT - actually BST)
Can I ask another question....
I like to use the F3 F4 and + and - keys a lot in my mask work. They are too far apart on my keyboard. Have you any PWP users who who have bothered with a small programmable keyboard?