Hello Destiny241,
Thank you, upgraded to 13.5.1, no help
Went into safe mode, no help
Created standard user, had to log into my normal apple ID to get messages to open, but still no help
Additional notes: I use about ten desktops and have specific apps assigned to each, and I know where they are always. This lets me ^arrow left or right across desktops to each app I regularly use without leaving the keyboard... which is way faster than using a mouse or trackpad. It makes things like cmd-v and cmd-c very fast. But it only works well if the app in each desktop goes active upon returning while I'm on another desktop.
Upon further testing messages is the only app that goes inactive if leaving that desktop, even if I don't click or type anything in another desktop. If I leave to the right it goes inactive but the cursor lines stays blinking and the three balls (red, yellow, green) in upper left stay lit. And you can't type without clicking on the app at least twice. If I leave going left and come back the cursor line is blank, and the three balls are greyed out and I still have to click twice to get the window and type screen active.
No other app does this including MS Office apps. And it occasionally does not do it, like just now ;{\
It's strange an annoying...