After the migration of IPs between two servers, sites are coming up with the default cPanel page.
This can be due to an IP mismatch. Make sure that the DNS records and the Apache VirtualHost for the domains are configured on the same IP.
Check the IP in “WHM >> Show IP Address Usage” and see if it matches with the IP you get on pinging the site from your local system.
If there is no mismatch then it should just be a case of propagation delay.