Blizzard is sharing with fans a list of known Ulduar [specific

] bugs they are aware of, but no hotfixes or solutions have been found at this moment to address them, which means these are on queue for a upcoming patch.

Blizzard Quote:
Here’s the current issues with Ulduar we’re currently investigating or are known and have no current fix.

Siege Engines that use Steam Rush while on a ramp sometimes fall through the world.
We currently have no fix for this, the workaround is simply to not cast Steam Rush on the ramps. The ability works fine in the Flame Leviathan fight and other flat ground.

Ignis sometimes will slag pot the offtank dealing with constructs.
The protections in place work most of the time, but we’re still investigating reports on this. Note that the protection is only granted if the tank is actively being melee’d by the construct. If players immobilize the construct and the tank backs away, the tank will not have the slag pot protection.

Kologarn can Stone Grip someone at the exact same time his right arm dies, leaving the player gripped for an extended time.
This is really rare, we located the issue, but a fix will have to wait for a future patch.

Kologarn can sometimes not respawn after a wipe.
UPDATE: We’re investigating this, but the current workaround is to soft reset the zone.

Mimiron will sometimes spray the room with his P3W X2 ability in phase 4.
UPDATE: We’re checking into this currently, and we’re combing through reports to try and nail down the specifics can trigger this.

Mimiron’s Aerial Command Unit can sometimes switch targets from the normal ranged tank to a different target in phase 4.
UPDATE: This behavior can be caused by the ranged tank moving outside the range of the Plasma Ball ability, which is 30 yards. We’ll update this in a future patch to create a phase 4 version of the spell with a longer range. The current spell has the shorter range to allow the ranged tank to move the Command Unit more easily in Phase 3.

Mimiron’s Assault Bots corpses don’t despawn after phase 3 ends, and they can hide mines with their bodies.
UPDATE: We’re going to have them vaporize after phase 3 in a future patch.

Some of the XT-002 Deconstructor adds can evade.
UPDATE: We’re investigating these reports.

The above isn’t the total list of all issues we’re checking out and fixing, some are visual only or are very rare.