I've seen the formation leader get blocked at the edge of the screen. Good thing to or they would have wiped me out.
You would think there would be some routine to prevent something like this from happening.
Ive had my fleets stuck on the edge of the screen to. damn annoying when u are trying to glass a planet and have to manually do the first few movements so the ai can take over
although as Marty pointed out, if u dont want the enemy to reach u its not a bug, it becomes a useful feature...
It isn't a great problem in tactical combat (you can always maneuver to "free" the AI ships), but once I had my fleet locked up on the map border in a PBeM game...