Error "Partner non admins are not authorized to sign in"

[SteveSoper]

Steps to reproduce

Logging in with an administrator account

Expected behavior

Admin screen where we can select Customers who can manage their own subscriptions

Actual behavior

Error "Partner non admins are not authorized to sign in."

Diagnostic logs

Unsure which logs are needed

Environment

Deployed Azure Web Store Builder a couple years ago. It has been running fine for years. Customers with access can still login and manage subscriptions. However, all of our admin accounts started throwing the "Partner non admins are not authorized to sign in" error a couple months ago. As such, we are effectively locked out. This has occurred for everyone with admin privileges and all users have global admin privileges and Owner access of all Azure resources. Nothing changed from a permissions perspective so my guess is that something changed with the APIs that the Web Store Builder is using. Not sure though.

[SteveSoper]

A little more detail on this error. It looks like the error is resulting from a failed PUT command to the Azure Blob storage. Still not sure how this error was introduced since this worked fine for years.

Command is:
https://storagexhoyn4qbgz3uo.blob.core.windows.net:443/customerportalassets?restype=container

Error code is:
409

[SteveSoper]

More detail... although nobody seems to be reviewing so not sure what the point is. The Azure Blob storage put command is failing because it's trying to create a container that already exists.

[SteveSoper]

Another update. The issue is not with the Blob storage but the fact that the application is trying to create a container that already exists. We haven't made any modifications to the application and so not sure why the sudden change in behavior.