I've had the exact same thing.

Switching to another unit in the same squad and back to the leader, leaves them un-animated. They stay hold the last animation(kneeling, standing, etc.)

steps;
Load the editor.
Place a group.
Set 'Player' and 'Playable' units.
Preview mission.
Press switch unit (default=U).
Move the unit.
Switch back to group leader and recall all units to formation.
Unit now has no animation.

:(

http://www.youtube.com/watch?v=pc2Q3vBj45M&feature=youtube_gdata