Solved Fixed

Plugins list and essentials config. If you're using PEX try groupmanager.

 

Try disabling
change-displayname: true

 

Are you using essentialsx?

 

Download the latest version here, http://ci.drtshock.net/job/essentialsx/ then try using nicknames.

 

Install all of them. Also try removing nametagedit, and maybe tabprefixes.