After swapping Proxy with Fletcher and then browsing to the quick match UI, I seem to caused the squad UI panel to not appear in the barracks anymore.
My current squad should have: Sawbonez, Fletcher, Skyhammer
I do not think I did anything else as I just started the game.
screenshot (notice the missing squad UI):
http://i.snag.gy/HLx1C.jpg
edit:
Ingame, I had Proxy in my squad. My change was not properly saved/accepted it seems…