Elk disappeared on boat today, interestingly I managed to get it back without commands.
For context I logged out in my boat and elk tied up to a fence post slot, came back the next day and after a certain amount of movement it started flashing until disappearing entirely. After a re-log it was missing from the boat but was still in the position it was when I first logged in; in the middle of the ocean.
What I think is happening is if the elk is on the boat during saving, it gets confused about where exactly it is and will try to restore it to its original position until it blinks out of existence. If you see your animals blinking or the saddlebag hitboxes drifting the best course of action currently might be to detach your animal, re-log, and then you can put your animal back and it should work fine?
If anyone is willing to corroborate thanks in advance.