I just purchased a new Mac Pro (maxed out) with the AMD Radeon Pro Vega II Duo 32 GB graphics cards. When I go to Preferences > Performance under Graphics Processor Settings the USE GRAPHIC PROCESSOR is grayed out. I read that it had something to do with the duo cards. After a few days of using photoshop, I went back in and noticed that use graphic processor was check and working correctly. Today, I updated MacOS Catalina to 10.15.6 and noticed use graphic processor is back to unselected and grayed out. It says Photoshop detected an error in your display driver.
I've noticed when it isn't working if I leave photoshop and go to another program such as Illustrator or Safari and come back to Photoshop, my graphic/image is grayed out until I click the zoom tool. This is what I am trying to fix.
Also, the same is applying to Illustrator since updating to a new Mac Pro. Under preferences then Performance, GPU Performance says compatible GPU not available. When I move a graphic it is acting very laggy. The GPU Performance and Animated Zoom boxes are grayed out and don't let me select either of them. I would think they would work with a brand new maxed out Mac Pro with Photoshop CC fully updated. Thanks
So I just fixed mine by accident last night. The usb c cable that plugs in my screen, I have it plugged into the spot with the lighting bolt on the back of my screen and then plugged into the back of the tower in one that doesn't have a lightning bolt ( I did 3rd from the left in the middle). It is now fixed plus I am able to use I design again, it was crashing every time. I hope that helps!