You did not crash, when you did a left click on that user?
If you still have your server or channel chat, then do me a favor.
Click and hold the nickname and then drag it into the channel chat.
It will result into a Client URL showing the Client ID, Client UID (Identity) and the Nickname.
And at the end it will show the shwon nickname from server tree.
Please copy the full url or the part =~Nickname]Nickname and then send it to me in private message.
And yes please update to server 18.104.22.168. This version blocks some invalid chars from mobile devices.
Btw you should also read the first 2 posts from