Azure account unlinked due to changed primary login ID on Microsoft account

I changed my primary identifier for login to my Microsoft account and now I cannot login to my Azure account.

Here's what happened:

1. I have multiple identities linked to a single Microsoft account e.g. ******@outlook.com; [email protected]
2. My Azure account was originally linked to [email protected], and I changed my primary microsoft identity from [email protected] to ******@outlook.com using the web account manager.
3. 2FA became required for login to Microsoft accounts and I set up MS Authenticator app. It generates an 8-digit code.
4. When logging into Azure, the new identifier [email protected] is recongnised, but it requires 2FA and a 6-digit code or push notification.
5. I re-linked authenticator and I now generate 6-digit codes, but these are not accepted by Azure login; nor do any push notifications appear in authenticator for login. Push notifications do appear for plain Microsoft account logins.

I think somewhere the two accounts have been unlinked, and there are now separate accounts for both Microsoft and Azure, each with different authentications and different 2FA configurations. However, I'm unable to login to Azure to setup its associated 2FA.

I do have access to the unique identifier for the Azure account and its associated billing information. How can I get this issue resolved?