Happened twice, both times attacking Pandoran Lairs. Had two ships with full loads, had to select 8 soldiers. Carefully did so, choosing some from each ship. Ended up with first ship’s 7 and top of next.
Worked around it by exiting and re-initiating mission.
Did you happen to go back and adjust equipment after selecting the troops? I found that when you go back to the menu to do either training or manage equipment, that the default selection of soldiers is reset and whatever you selected is ignored.
Ah thank you OdinSon. I had this bug several Times and now i will be able to avoid it