I just experienced a bug with the STF queue. Unofrtunately I was AFKing a lot so I won't be able to describe all the steps to reproduce the bug but anyway.
I've queued myself for khittomer accord ground elite with My KDF char. I think I missed the first alert popup to engage (I was afk), so I queued myself again and got a "no possible map" error. Since it's not the first time I get this bug, I beamed up since it used to solve the problem before. Then I queued myself again for the same mission and got a 10s timer for an immediate start.
Then I got the STF leaver penalty for 1h without any timer at the bottom of my pve queue list, and I was still able to see the missions list. I had to log out and in again to see the normal stuff happening.