I have come across a bug a few times now where if you relog or disconnect during a zone in, when you return to game the zone-in is gone BUT then when someone tries to exit and re-enter the instance to zone you in again it does not apprear.
This wasnt the end of the world as we dropped a guild banner outside HK and they walked in manually.
However it caused major issues when a player didnt have quantum sight a few weeks back when we zoned into RotP and this bug occurred so they could not walk in manually.
Anyone else experianced this, its caught us out a couple of times now.