https://forum.nostalrius.org/viewtopic. ... 58&#p90266It's a known bug with the chat channels. Happens when someone DCs and reconnects, sometimes the channels don't recognize you DC'd and still thinks you're in the channel.
Have you tried to /leave the affected chat channels and /join them again? If that doesn't work, I've found it usually fixes itself after logging out for like 30 minutes.