I was invited by some random dudes, this is the first time i had to use chat window. I have no idea how long this bug has existed. Hopefully it is just an isolated instance. I will try more times when i team up with guild mates later.
The chat bug is still there, it happens anytime anywhere inside dungeon, not just the spawn point. Now no one dares to open chat window in dungeons, it is especially difficult when play with random players. IMO it is a show stopper bug which needs to be addressed ASAP. Please forward it to the dev team, thanks in advance! @Buck