The domain troubleshooting guide can help with most custom domain configuration issues. You might be able to use that guide to solve it before a human is available to help you. Then you can come back here and share the answer for bonus points.
You can also use v0 to narrow down the possibilities.
I too am having the same problem. I have deleted and recreated my project many times. Each time I re-enter the subdomains ops.v…com and *.ops.v…com. Always worked like a charm in the past. However today it is not permitting the addition of the subdomains with an error that they are already associated to another project. When I look it shows the subdomains in what I would have to refer to as an unassociated (maybe orphaned) status and I cannot clear them so I can add them back. I have tried all of the recommended CLI steps I can find in the literature/forums with no success. Any suggestions on how to get these cleared would be greatly appreciate. Project is dead in the water until I can get this fixed. Thanks