Hello there,
You can check the latest Known issues in FIDO2 security keys in Azure AD and see if you can find the issue, If not it is suggested to use the feedback app to report the issue.
This article covers frequently asked questions for hybrid Azure AD joined devices and passwordless sign-in to on-prem resources. With this passwordless feature, you can enable Azure AD authentication on Windows 10 devices for hybrid Azure AD joined devices using FIDO2 security keys.
Troubleshooting for hybrid deployments of FIDO2 security keys in Azure AD https://learn.microsoft.com/en-us/azure/active-directory/authentication/howto-authentication-passwordless-troubleshoot
Hope this resolves your Query !!
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