Photoshop 2021 having flashing problem

I updated to Photoshop 2021.0.1  Running Mac Catalina 10.5.7  I have a 27' Imac. 3.8GHz Quad-Core intel Corei5, (2017) with 64 gb of ram, Radeon Pro 580 8GB Graphics card.  When I'm working and leave photoshop running in the background, while I check my email, or go back to bridge, or whatever, the last photo I was working on flashes black very quickly. Sometimes, just sections of the photo turns black. When I click on it, it comes back. I should have plenty of power to run photoshop! My laptop, which is a little older, is not have this problem!   I tried unclicking UseGraphics Processor in my PS preferences, but that didn't help. 

Anyone else having that problem?  Should I just try uninstalling and try again. It makes me worried that it's the graphics card on my computer, but it doesn't do it with any other software, only photoshop! I'd been tempted to go back to 2020, but I'm a real estate photographer, and I love the Sky Replacement. I've always done it with layers and blend modes, but this is quicker!