Hi @J. Kellner ,
This has happened to me with the NPS extension before. I eventually found the trace logs and had a DLL error and was able to resolve this by reconfiguring some of my settings in the extension, enabling Azure Multi-Factor Client Auth (which was disabled in my tenant), and downloading the most recent version of the NPSExtensionInstaller. I also had multiple certificates configured and had to remove the extra ones. (My setup had a lot of things missing, which probably won't be the case for you.)
Some things that help:
- Check the Auth logs in the event viewer.
- Check the MFA server logs
C:\Program Files\Multi-Factor Authentication Server\Logs. - Check the MFA logs from the Azure portal itself - MFA Portal > Usage > User Details
- Enable MFA Client Auth if it's disabled.
(Screenshot won't attach but it's under "All Applications.")
If you're having trouble getting a support case created I can also enable one for you if you send your subscription ID to AzCommunity@microsoft.com