Blacklisted characters?

I’m an officer in my guild, and while playing the other day I got the following message come on my screen. “Blacklisted (character name I won’t write here for privacy reasons) is in your guild”. It was a black box in the middle of the screen, white outline with the ok button at the bottom.

He/she’s not in the ban list for our guild, I could find no reason why I would’ve gotten this message. I opened a ticket, and was told that Customer Support is not aware of any reason why this would’ve happened. They strongly suggested I post here so it can be tracked and maybe I’ll get input from someone else this has happened to.

Anyone ever deal with this or know what it is?

Never even heard of this happening. Potentially an addon? Otherwise, I am unsure of why or how Customer Support couldn’t have helped you with this.