Not sure if you have solved this yet, But in case not, I'll leave my input. Try adding essentials.pay to there perms. If That dosent work just per - g:essentials.admin under inheritance. This will give them every command for essentials. Hope This Helped!
The Meaning of Life, the Universe, and Everything.
i think you have this thing (') that what make you the permission is disabled
If you dont bealive me.. you can do this /manuaddp [playername] essentials.pay
then ask them if them can use /pay or not ..