As we all continue to explore patch 3.1 on the live servers, there's bound to be bugs popping up, despite the work done by both Blizzard and players on the PTR. Blizzard poster Daelo has already created a list of known issues with Ulduar and is updating it as more information becomes available.
There is currently no fix for the fact that Siege Engines that use Steam Rush while on a ramp sometimes fall through the world. The two trash pulls in front of XT-002 Deconstructor are linked, but a soft instance reset should hopefully find the trash no longer present, although a full server restart might be needed. And they're currently investigating reports that players are being melee'd by Ignis the Furnace Master while in the slag pot.
Keep reading below for the current full post, and keep checking it for any updates. Have you noticed any issues that are not on Daelo's list?