Can't rejoin split fleet?

[StarJack]

62 ships attack a planet with 15 mines in orbit, get message 14 mines were swept, had enough sweepers to sweep hundreds. Rout the planet easily, apparently took no damage. Fleet splits, like it often does after a combat, regardless of whether I win or lose. (rolls eyes) The past 3-4 times this has happened I've been able to move one or the other split fleets back ontop of the other and they magically merge again. (You get a free fantasy game with this scifi game!)

This time, no dice, I've renamed fleets, spun a couple turns by, can't move the fleet over the planet (named WTF for obvious reasons). The fleet trapped planet should have forty ships in it but shows up empty when right clicked. Whatever defense they used, I want it. Make people think twice about attacking you if you get to magically whisk away 60% of the attacking force after they splatter your planet!

I'd read about the fleet splitting bug when you retreat, there is also a splitting bug when you win.