Blizzard has confirmed lag and disconnect issues in Nerub-ar Palace and a fix is coming.
Ever since the start of Patch 11.0.5, the Nerub-ar Palace raid has been lagging causing some bosses to bug out. This has been very frustrating for guilds and they are currently working on a fix as some of the encounters are severely unfun when you die due to no reason of your own.
Disconnect issues were also common on Queen Ansurek on all difficulties, especially on the first pull of the night.