Though I kinda explained it in the title, one crew from the trade station somehow got stuck on the merchant ship and froze up while holding a steel plate, making the ship unable to move
The ship acts as if it's entirely missing a move command, as it does not try to return to its original location or orientation when pushed
Attacking the ship seems to reset its behavior the same way that ships with crew onboard from another station or ship act normally, which is how I noticed the crew did not belong to the ship
I've included a save file with a few gifs I think are helpful