log into root SSH on the machine and do the following:
cd /var/cpanel/users
ls -lah username
cat username
permission must:
rw-r----- 1 root username 596 Jun 8 14:03 username
Inside the file, the USER=username entry should have the username of that user. Some 3rd party plugins modify the username by appending .sometext to the end of the username. This can cause cPanel to be unable to read the user’s file.