There is a bug in morgue section of The Tombs mission. If you get rogue agents in that room and kill them, you cannot progress into the next hallway due to an invisible wall. Everyone has to suicide with grenades to clear the bug.
Every single group I've been in knows about it and they just die on purpose just not to encounter the issue.
This bug has been around since WoNY dropped and you still haven't fixed it.
Hey Agent, We are currently aware of this one and have looked into it, a fix should be coming with the next Title Update.