Running the latest version of Affinity Photo. I've ran into issues where Affinity Photo will not respond accordingly. Below are two examples. (P.S. This is for Windows 10)
1. Forgets that I'm painting onto a mask. It's happened more than once, where I've been creating a mask by painting black, white or grey onto it. Go and apply a layer adjustment. Then come back to the mask and it's treats my painting as if it was a regular pixel layer. I've deselected layers, gone back selected the mask layer. If I step back through history or delete the mask and start over, it works fine until the next time.
2. Luminosity mask. Perform a Control+Alt+left click on the thumbnail and it works fine. Go and apply adjustments. Come back to create another luminosity mask by using the same Control+Alt+Left click and it doesn't work.
These issues seem to happen after I apply layer adjustments. Sometimes stepping back through history will allow me to do what I need to do. Or basically wipe out layers and start over again.