After searching this board for a solution without success and waiting over 6 hours for a response from support I give it a shot here.
Running the domain on https://dnschecker.org shows green marks for A record and CNAME but the domain is not accepted because of the error mentioned in the subject field.
In the last 10 years never experienced a DNS resolving from more that a few hours max.
But now when I enter the domain this message shows: Only one step left!
But still getting the CNAME entered incorrectly error. A bit frustrating to say the least. This, in my opinion, proves the error is clearly on the shopify side.