Hi James Boyt
Thank you for reaching out regarding the issue with MFA not prompting at admin.microsoft.com.
To help us investigate further, could you please share the details of your Conditional Access policy settings, especially those targeting the Microsoft 365 Admin Center? A screenshot would be great to help us understand the configuration more clearly. If you find it may be inconvenient to share it here, please feel free to comment, and I’ll PM you directly so you can provide the screenshot privately.
Additionally, if you have a test user configured with the same Conditional Access settings, could you confirm whether that user experiences the same issue? This comparison would be very helpful in narrowing down the cause.
Please understand that our initial response may not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution.
Looking forward to your reply.