I do have Metal Compute ticked. Here is the file, it is not flattened at the moment. This morning, when I tried to flatten there was no problem, however last night I tried 4 times and it always came out with the checker pattern.
It seems that the first file I work on will go somewhat smoothly for a bit, and then things will start to glitch, slow down, or freeze. If I close everything sometimes it will be back to ok, or it will still not run smoothly... Yesterday the program restarted my computer unexpectedly twice.
The major slow downs seemed to start when I tried to create layer masks in an adjustment layer. I used the paint brush tool to modify the adjustment layer and often there would be a significant lag, or the computer would shut down.
Previously this would happen with the dodge and burn tools as well.
Side note, I have also noticed that the denoise options do not work...
kristen.tiff