Issue in registration process

I've had the same issue and it took me forever to figure out how to solve it.

Turns out you can create a partner center ticket even if you have no access to a partner center workspace yet, using the following form:

https://partner.microsoft.com/en-us/support

The support staff then had me create a new partner account with a slightly different company name. They said I can change the name back later but that wasn't even necessary as the new company already ended up with the correct name. After that everything worked.

Hope this helps you.