I had this bug a LOT pre-2.4. I haven't gone in a frontlines match since the patch mostly because the queue has been terrible even for TA when I've tried, but yeah, it only ever happened in FL for me.
Shame cause I need 4 more wins for my pony, but I can't be bothered. My sympathies, regardless. It is incredibly frustrating. I remember getting kicked from a match because of it.