A system review shows there was an issue with .COMs processing changes on 10/16/2019. It was cleared up in the same day. If you were making changes to .COM domains and are still unable to do so now, please contact our support team at one of the numbers in the link below.
If you're trying (and failing) to make changes to a CCTLD, Please use this link, and click on your specific domain ending to see if there are any restrictions regarding the update to nameservers.
TLH - GoDaddy | Community Moderator Supporting you at x.co/247support