Probably not a “bug” so much as “feedback” but it’s sufficiently annoying that I’m calling it a bug:
Currently, you must be logged in for the end of an invasion or you will lose all your troops, because they start falling off due to the lack of facilities to house them on the planet. You need to log in and get them all back on the ship.
After an invasion, troops get 24 hour immunity where they won’t tick down even if there are no facilities to house them. This lets the player setup an invasion and log out without having to worry about being online when the invasion completes, to fix his troops.
Alternatively, you could just automatically send them back up to any available ships once the invasion is over.