Here's the sequence:
(1) Start typing something in group-chat...
(2) Person in group leaves, disbanding the group...
(3) Finish typing, hit enter.
(4) Message is sent to general chat.
This happens in various configurations with different chat channels, but the gist is the same: people leaving and joining party chat can cause your messages to go to the wrong channel. This is, IMO, the worst bug in game at the moment. I know that the cause is straightforward: the channel no longer exists, so the game changes the default channel while you're typing. I'm saying that that is simply the wrong behavior.
Why is this still happening after so long?