If a scanner or surveyor is en route to an occupied planet which is abandoned while they are in flight, they will turn around and fly back to the sending planet.
In theory any ship that can go to an unoccupied planet will have this happen. Not a huge deal, but unexpected.
What should happen?
Instead of having them return to the sending planet, they should continue. Ships that only target occupied planets, should turn around as they do now.
This is a low priority.