Thank you for posting your question in the Microsoft Q&A forum.
Please understand that our forum is a public platform, and we will modify your question to cover your account information in the description. Please notice to hide these personal or organization information next time you post error or some information to protect personal data.
You’re asking how to fix sign-in issues with external Teams resources after migrating from Google Workspace to Microsoft 365 using the same domain, and why your account sometimes isn’t recognized in MS365/Azure portals even though email works.
Based on your description, because you previously logged in with a personal account, but after the migration, your account has now been converted to a business account, you should log in using the link designated for business accounts. Please use the following link via business account link to check whether the issue still persists or not.
Here are different examples between personal account and business account
I hope it helps, if you have any other questions, please feel free to reach out
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment"
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.