http://i.imgur.com/Ol8A0Nk.jpg
I have auto-join mumble on lobby start selected and this happens all the time. It just happened 1 minute ago, demoman on pl_upward. I clicked the link
But get brought to mumble and it says DEMO is already taken, even though the link above clearly has b33p etc. in it.
Now with the mumble integration thing, it thinks I never join mumble.