I had this also.
When frighting the last boss in vet Blessed for the first time, you will most likely wipe since people don't evade the lava, thinking it is just something their healer should heal through.
So after the initial wipe, we were stuck in combat, and could not climb the ladder to the HM scroll.
Thank god there is another bug, where one can jump to the upper platform on the edge of it.
So we managed to re-activate the scroll and beat it with some simple lava dancing.
I actually encountered another bug in that dungeon. The bosses in the penultimate arena can actually aggro if you cast an AoE just at their enclosure gate. They clip trough it and attack you before it's open. With the shalks and the huge scorpion that's not an issue, but the troll animation is linked to the script that opens the door to the next area. One of the DDs actually made him clip trough the door by casting eruption, he came charging, we beat him quite fast, the gate opened during the fight, but the door remained closed. We had to redo the whole dungeon because it won't open even if we all left that room. We were close to wiping at the end boss, because the ground attacks are one shot now. I'm sure I wiped before though, because I played a lot with PuGs but never remember getting stuck there. So the bug is brand new