Just had that happen to me, too. Was playing the Shore Bombardment mission and ordered my two harriers to RTB once the mission was accomplished. They refused to land on the carrier. The Super Cobra I had launched touched down just fine, but the Harriers just circled like idiots. Tried stopping the carrier, cancelling and resetting the RTB orders, nothing worked
.
Had another strange one happen to me in the Strike Back mission. The enemy had a command center remaining and I tasked the units with air-to-ground weapons (Super Cobras and warships) to take it out. They'd acknowledge the order, eagerly move within range, and then break off and head off with their backs to the target without firing as much as a cannon round
. Damned bizarre.