This might be better suited to discussion in the UI forum, where there is in fact already
a thread on the topic (link)
Edit: As that thread points out, it can be a mod that seems entirely unrelated to raids. MoveAnything was really bad about this, update it if you have it installed. Keep your mods at the latest version, and when possible avoid using ones that haven't been updated for a few months, since something could change underneath them and cause really weird UI errors like this.