Displaced ships caught in loop

Anyone have this issue? I just noticed it in the last few games I've played. For any planet that I win by influence, any displaced ships head for their nearest friendly planet, but get caught in some kind of loop where they spend their moves heading for their planet on one turn, and then on the next turn, head back to the original starting point. As far as I can tell, they will stay in that loop for the rest of the game, or until they are destroyed.