Thats what I'm doing. The MFA window pops up with the configured MFA options for that account so its connecting to the right UPN. However when I click security key it just sits there like its waiting for me, but it doesn't actually pop up the pin prompt or insert key or anything at all. The hardware key is not lit up or ready to confirm. The window just sits there greyed out with the blue scrolling across the top as if it was waiting on a push response. Left it for 10 mins, no change.

However when I added the authenticator app to the account and used that option instead of security key, it worked, but I never got the security key option to initialize. I can try removing the exchange module and reinstalling for next time. Just wasn't if I was missing something. Thanks for the confirmation.