I started a solo run of tier 2, and got to the second floor to discover two things amiss:
1) There were two mineral rooms
2) There was no party button or elevator.
I'm guessing the erroneous extra mineral room overwrote the path to the exit.
...So I started the run over. :(
(Was playing as my second character, Keltis.)
Edit: Not sure if this one's a bug but now I'm hearing the Construct stage music in a Fire-Construct stage when normally it would always be the Fire stage music. Or maybe it was previously bugged to have the status theme always override the creature type theme, and now it's actually been fixed to sometimes play the creature type theme instead?
1) Two mineral rooms are normal. I see such layouts once in a while before the latest update.
2) This seems to be a bug introduced in the latest update. When you "Go solo" you might encounter that bug with elevators. See the other threads about elevators or looping fix.