FFXIV Disappears after going away from keyboard.

[Reih]

Check Settings/Privacy/Background Apps and see if your game happens to be in the list and turned off.
As you run the game in Windowed Mode, it can loose foreground if you are not active in the game or have something else also open/running, which Window 10 may decide it to be a background app at that point and subject to power management restrictions when idle.

Nope, not in the list.