I encountered something very similar when i played today. I fast traveled to the raid bivouac, got in the boat on the left and went to the raid entrance. Then i fast traveled back to the bivouac and tried to get in the boat on the right.
When i did this my character swam a bit and then got stuck unable to move, interact or do anything. I was able to roll once and then i was completely stuck. I couldn't even fast travel since the game thought i was still in an interaction. I had to log out and back in to be able to do anything again.
My guess is the game has an edge case in the vehicle interaction logic where a player can try to enter a vehicle but if the character moves in a particular way - maybe out of range of the seat the player is trying to enter - it gets stuck trying to enter without being able to do so.
Appreciate the details SoloKiller, thanks bud.