I've tried a few things, and found something out.
I had three layers, a background image, a foreground and an invisible copy. If i delete the hidden layer then flatten the image the glitch stays, but if I simply flatten the full image the issue goes away. Having layers or merging layers still causes the issue, but flattening the image removes the glitch.
Its still not ideal, I don't want the background and the fore merged while doing shade work. but its new info.
I'm also using 2.10.8 now, no other changes
I had three layers, a background image, a foreground and an invisible copy. If i delete the hidden layer then flatten the image the glitch stays, but if I simply flatten the full image the issue goes away. Having layers or merging layers still causes the issue, but flattening the image removes the glitch.
Its still not ideal, I don't want the background and the fore merged while doing shade work. but its new info.
I'm also using 2.10.8 now, no other changes