Recently, I've had the problem of while in a mission, your teammates will suddenly be invisible to you for no reason. This makes you unable to heal them or otherwise assist them, even if you can still talk to them. The fix is for one of you to zone.
I've noticed it happening a lot in the mission with the main corridor 6 branches layout, and in the cave mission with the big main room that has the fireplace in the back left corner you can walk through.
Has this happened to anyone else? Does FC know about it?
Thanks.
-A