OK. Both of these were missing their IPv6 address for some reason...users with IPv4-only connections are actually able to see your site, but those who are v6 capable were not because the IP was not associated properly. We've seen this before, and it's believed to be related to the fact that both of your accounts were cPanel migration accounts.
I've corrected the IP associations on your domains and it should go into effect within the next 2 hours.