Happened a number of times, and I had to revert to previous saves. At first I'd lose all my items, and they'd be nowhere to be found - lately the items disappear, and then immediately 'unlock' again (incl paid items and unlockables), and become available in my inventory. But I'm kinda naked and would have to re-equip everything (I load a previous saved game to avoid that).
I've managed to repro this today (on Xbox Series X) by
click the Xbox Guide while playing (to check friends, for example or a message)click the Guide again to come back to the game.Repeat, and boom. If it doesn't happen the second time the guide comes up, it always does on the third time.
Confusing bug, but I do hope it can be resolved, as it affects engaging with the console/dashboard etc.
Thanks 🙂