Hey, I had that happen to me yesterday (destroyed last enemy, and kept hitting the done button, but APC never moved). However, once I moved one of my mechs close to the APC's, they started moving again. It maybe actually fixed. Next time if you run into a stuck APC, try moving a mech (or your whole lance) near the apc, and I'm pretty sure it will fix it.
Reloaded the game from last night and all I have to say is:

Thank you very much Sir, it worked for me too.