Save Bugged Out?

Somehow the save for one of my characters is bugged out in a very odd way. There don’t seem to be any noticeable problems other than one thing, which is that when playing online with another player hosting, nothing i do on my character gets saved other than guardian xp and whatever loot i put into the bank.

Any quest progression/inventory/skill changes reverts to whatever i had started out with. This only happens after joining another player online though. I can play alone and none of the previously mentioned issues happen at all.

Does anyone know what could’ve caused this, or if i can somehow recover that character?