no clue. I assume it's related to resetting the world too many times (since this boat was the one I got directly after I did my 14th reset), but it could also be related to my switching in and out of the tab quite a bit.
I had the same problem, I also think it might have something to do with playing in a reset? Or in my case, my parrots attacked and the cargo was gone and the ship should have gone down under but it was still there.