Already looted

While I'm killing mobs, a few of them say 'already looted' when I try to loot them, which causes me to not be able to do some quests. The mobs where this has been occcured were grizzly bears and shardhorn rhinos in grizzly hills and sholazar basin. Is there anything I can do so I can loot them? (I've tried reload/ restarting the game, does not help, in some cases when I restart I can't kill any mobs since it says 'invalid target'.)

I have the same problem and tried everything that you did as well. Doesn't work. It's very frustrating.