Not sure if I can accurately diagnose your problem however a quick search of the issue revealed some links that may help you diagnose it.

https://forums.unrealengine.com/t/standalone-game-full-screen-goes-black-after-minimize-and-restore
https://www.reddit.com/r/obs/comments/doh9zn/display_capture_black_screen_with_full_screen
https://learn.microsoft.com/en-us/answers/questions/2730933/black-screen-issue-for-exclusive-fullscreen-mode-w?forum=windows-all&referrer=answers
https://steamcommunity.com/app/462780/discussions/0/154642447913586476