How can I resolve access issues with the Microsoft Learn Sandbox using my personal account?

Question

I am trying to complete the Azure Fundamentals Training and cannot access the Sandbox. On the left side of the screen it will indicate to me that I have activated the Sandbox, however, the right side of the screen (where the Sandbox should be) prompts me to sign in.

To sign in I use my personal email, the same as what I use for my Microsoft Learn account, and get this error message:

Selected user account does not exist in tenant 'Microsoft Services' and cannot access the application '18fbca16-2224-45f6-85b0-f7bf2b39b3f3' in that tenant. The account needs to be added as an external user in the tenant first. Please use a different account.

This question has already been submitted at least twice, once here as a Microsoft Learn Q&A Submission on 1-27-2025 by @Topel-2681, and once as a Microsoft Training Support Q&A on 1-28-2025 by @Andrii Ihnatiuk . Neither of these submissions have been sufficiently resolved.

Do not tell me to try a different browser or Incognito Mode, I have tried that. Do not tell me to try to contact MS Learn Support, you cannot contact support, you can only provide feedback without any hope of follow up, and I have already done that too. Do not tell me to go through Azure Support, I cannot contact them or create a ticket because my account does not "have permission to create a support request."

I have an Azure account, but it is just a personal 12-month free trial, not affiliated with any organization or business. The same goes for my Microsoft Learn account in the sense that it is also just a personal account and not connected to a larger organization.

However, Microsoft Learn is supposed to be a free, accessible learning tool for everyone, and not restricted to business accounts. I am able to use my personal account to access the courses and other Microsoft Learn content, so why can I not use all of the learning resources within the courses?

Why is this a consistent problem with this program and how can it be resolved?

Regarding the AZ-900: Microsoft Azure Fundamentals course.