So we tried like 6 times and there are no geysers to proceed with mechanics. We left dungeon. I think my money, though, will not leave my wallet for a long time now lol
I have encountered this twice tonight. I queued in as a replacement for the second group and wound up with the queue penalty because of it.
Basically, on the first group I had (before we were aware it was bugged), we were able to get Xal Nur's first spice phase to go off properly, but after that, he went invulnerable without summoning the spice at all. It did not matter how long we stayed there - Xal Nur would not summon the spice for the mechanic. We tried burning him on other attempts only to be met with the same result: an invulnerable Xal Nur.