In the 3rd mission (not sure), probably called aerial superiority or something like that (have it in French), the medic (8) cannot treat his teammates (7 for sure, the others I don't know).
He goes, play the animation, and at the end, he stays blocked (actually the 2 stay blocked).
I have no mods, nothing added... Have already reported multiples bugs and always had standart configuration.

Edit: actually, 7 is blocked, so he's the one with the problem: he cannot move nor get back into formation and also as you understood he cannot get healed.
I let you do what you want with this ticket, because it's a bug, but probably not reproducible...