After the last cpanel update, random user accounts can not login into cpanel or whm

[mraberration]

After the last cpanel update, random user accounts can not login into cpanel or whm. I can't find the similarity between the accounts that can't login but it seems as about 1/3 of the accounts are locked out from cpanel. They can login via ftp with the correct information.

I have tried the following:

Reset the users passwords.
Suspend/Unsuspend the account.
Upgrade/Downgrade Cpanel to all possible options.
/scripts/fixeverything

This is really weird because the accounts are not able to login to cpanel, but can login to everywhere else, also not all accounts are affected, and the ones that are are on different plans/skins different age (new/old accounts, resellers and users...


Any help would truly be appreciated as people are starting to get pissed and I am stumped for the moment. Thanks if advance for any replies!

[DigitalN]

Are there any clues within

/usr/local/cpanel/logs/access_log ?

What error do you get when trying to access? 404, 403 denied or other ?

Are the users files correct in /var/cpanel/users/$user ?