Can someone help me get rid of this X?

The x that’s on the upper left hand corner of the Mastery skill? I swear I’ve tried everything but the uninstall button at this point.

check:

ui/skills/classX/classtable.dbr

for invalid entry in:

tabSkillbuttons

Make sure each button points to a valid skill.

Looks like a skill UI with an undefined x,y. Remove it from class table like Kath said

Fixed it, thanks guys.