Start "create docking" on 1 entity but don't finish it. Exit your ship when you have selected a location to put down a rail docker. Enter another ship and the create docking feature will still be enabled, placing down a ship core and then confirming its rotation will create a weird result.
How to reproduce:
# use "create docking" on 1 entity, select a rail docker location but don't do anything else
# leave that entity and enter a new one
# notice that you still have the "create docking" enabled and that you can finish the steps too. Upon creation of the ship core, it will be a broken dock.