version 183.641 Affinity Photo
I can reproduce this bug
The bug does not happen for a new document
Here is an accurate description of the problem...
Conditions:
Using Windows 10
The problem: This will occur with any 2 image files. You open a jpeg and then use Impainting brush or unsharp mask. Everything works as it should. Close the document but leave the program operating, and then open another jpeg, and then try to use either impainting brush or unsharp mask, and neither works as it should. To get it to work, you need to exit the program, and then restart it. Then everything works fine again.
Computer hardware is a 1 year old DELL Inspiron with a graphics card and AMD processor Rizen 7. I am using a 500GB flash drive for drive C, and assigning all of my Windows 10 categories to an 8TB hard drive in drive D, such as desktop, documents, music, videos, pictures, etc.