I have run into this and found the owner had the monitor plugged into the onboard video connection. We shut down, moved the monitor to the graphics card, booted and it was fixed.
Hope it's this simple thing.
One day I noticed some Steam games were open but not visible. They would show in the taskbar and you can hear the games and see the custom cursor. Tried all kinds of things and gave up. Later found that Photoshop and Krita (similar to PS) would open fine, but when you open a photo, you can see the file name in the title bar but could not see the pic or the little window it pops up in. I found out I could take a screenshot in Steam while in those games, and I could see the game in that picture. Tried it with the Windows screenshot, but that didn't work. Though I didn't try every app, I know many games and apps were working fine. Reloaded programs, didn't work. I finally did a full reset, reinstalled windows and cleared out drives. I reinstalled the problem games and apps (fresh downloads) and problem is still there. I'm wondering if this might be a hardware issue. I hope somebody here has had experience with this, I've been searching for a while and haven't found much.