Odd paint brush behaviour

[kalee]

I am running the latest 1.9.1 suite on windows 10.

In photo, I realised that I could not use the brush tool on a layer mask, to either mask or unmask the layer. This is repeatable on an existing or new document.
I have uninstalled, and re-installed from a fresh download - same result! As I have 1.9.0 on another machine, I tried that one, and all is fine. Updated it to 1.9.1, and all is still working.

Going back to my original laptop, I then tried the same thing in both Designer and Publisher - and the brush behaves as it should do on a mask, but not when I went back to Photo.
I have since realised that my paint brush does not work in Photo on a blank pixel layer in normal paint mode. It needs a fill layer to actually function1

This has got me baffled, so any help appreciated. Unfortunately I have no idea how long this problem has existed, but wonder if there is some odd interaction between the three programs?
It is not a case of blend mode stupidity - it is all set to black or white in normal mode, with brush parameters checked.

Edited March 11, 2021 by kalee

[Gnobelix]

Hello @kalee,

Welcome to the Forum.

may be that protect Alpha is enable.

 

Cheers

[kalee]

Thank you very much, Gnobelix - I would never have found that in years if you had not posted that screenshot!
My 15 inch display does not show the protect alpha setting. Had I not then clicked the double arrows at the end of the toolbar, I would never see brought it into view.
Being as the other two programs function normally, I was going down the wrong track in my thoughts.
Thanks again.
 

[Gnobelix]

You’re welcome.

 

Cheers