On a slightly unrelated note, I was setting nameservers for two .de domains a few weeks ago and thought my provider was being crazily strict because they kept getting rejected. Turns out you can't point to a nameserver until that nameserver has a zone for the domain, and you can't use nameservers from two providers unless those two providers are both in the NS records at both ends

Common paint point with DNSSEC. It’s brutal in the domain industry because when you buy a name with DNSSEC enabled it oftentimes can’t be setup to resolve due to these sorts of issues. Typically seller needs to deactivate first.