WotLK When you enter instance this weird bug happens:

[Tekaru1958]

https://imgur.com/a/eiwCcxx

[angrylol]

I had this sometimes, but then I got that large address aware tool, have not happened again.

[shhnedo]

but then I got that large address aware tool, have not happened again.

I've been using LAA for a long, LONG time now, and it still happens but very rarely. I don't know exactly what causes it but I imagine it has something to do with you loading in and the state of the connection in that exact moment when you have to zone in at the specific x/y/z coordinates of the floor in front of the door. And it's not just ICC, it happens in other raids and dungeons too.