Duoed this instance tonight (12/5), both toons progressed, neither being stuck as previously warned. Leaving warning text in place, in case it comes back.
(Note: He does not attack you. This is a scripted story event that cannot be failed.)
start attacking him till he says "It will magnify Nostrolo's song! A legion of maedjinn will soon spill forth from their wroughtlands, and all the planes will have you to thank!" then use the Glorious Maestra's Cithara and DPS him down.
Enter the Virtuosa's Prison
Take the portal at ( 848, 70, -14 ) Copy/waypoint 848, 70, -14 to Vaashkaani Bastille
Speak to Lyrissa Nostrolo ( 375, 23, -356 ) Copy/waypoint 375, 23, -356. group update
Set the arca down ( 383, 23, -355 ) Copy/waypoint 383, 23, -355. group update
Speak to Lyrissa Nostrolo again. group update
Defend her from attacking djinn.
defeat the attacking djinn
Kapuji-bashi Haakhaz will spawn, defeat him as well
Speak to Lyrissa Nostrolo again. group update
Speak to the Allyrians
Helalli, Chandrima, and Vahravi will spawn. Speak to Vahravi. group update
After a discussion, everyone will disappear.
Take the portal at ( 367, 20, -335 ) Copy/waypoint 367, 20, -335 to leave the zone and return to Miranna Ameema in Zimara Breadth