Greetings!

It is difficult to say what the issue might be. However, in most cases such as this the issue falls under one of these two:

1. Propagation. Although a misleading term, it is the universally accepted term for it. At 72 hours, this is unlikely to be related.

2. User error. It happens. It’ll happen to me before I finish this post, we all overlook things from time to time. Double check spelling, make sure the domain is added as “domain.tld” and not “www.domain.tld” or something like that.

You can use something like this to help you investigate a bit:
https://mxtoolbox.com/dnscheck.aspx

Do note that DNS testers, such as this one, are prone to reporting things that are not problematic. They can be used as a guide, they should not be used as the final authority on the definition of perfection.

Jarland