Thanks for looking into it! I have been using all lowercase - I don’t think the send messages would work either had I not been able to join the channel at all. I’ve also tried it on another channel with the same results.
mIRC works fine with both sending and receiving messages, but my Unity client can only send. And my Unity client user doesn’t show up in the user list in mIRC when I’m running both (connected to different accounts). The reverse is also true; my Unity client will only display its own user in the user list.