'Equipment' and 'Backpack' Tab Sync to Party Host After Exiting Multiplayer

Players report that joining a multiplayer session before later exiting back to single player causes their Equipment and Backpack tabs to disappear, yet rejoining a multiplayer session with the same Host player will cause the inventory and equipped items to reappear until exiting the party again. 

Workaround: Continue playing with the same party host until further notice.