IPs not blocked but cannot access cPanel or Webmail

I recently migrated around 20 cPanel accounts from shared hosting to a VPS running WHM.

Most of this has gone fine, but one account in particular is having some strange issues:

They could not access their webmail, cPanel or website from two distinct IP addresses (home and office), neither in a browser or using a mail client like outlook.

The website in a browser would come up with site not found, even though the site was resolving everywhere else (and it's unlikely it's a DNS issue as the domain was edited a week ago and all other accounts have resolved fine).

I temporarily disabled firewall and whitelisted their home IP address in WHM's ConfigServer Security & Firewall area, which made the website load in their browser, but when they try to access cPanel or webmail, they are able to access the login screen, but the username and password come back as invalid. They are definitely using the right info and I am able to login from another location using the same username and password.

Note: I have whitelisted the user's IP adress (where they are trying to access the server from today) in both the WHM firewall whitelist (config server security) AND in the individual cPanel's cPHulkd area.

Any idea why they are still locked out? Are there any other ban lists I'm missing?