Hi,
    i am currently doing the above mentioned challenge in the salesforce trailhead. I creatd a permission set and assigned it to the user like it was mentioned and even logged in using the two factor authentication method. but still it is showing challenge not complete. Is there any reason to this. I don't know what i am missing. The following is the error message i received

Challenge Not yet complete... here's what's wrong:
Could not find a user's successful login using two-factor authentication. Make sure you successfully login at least once and that you are prompted for a second factor of authentication

Any help wpuld be appreciated