We have a policy set that the basis of authorization is the password + a second level of MFA such as Okta Verify. Unfortunately, for such a set it is not possible to add an additional MFA in the form of Yubikey or Goole Authenticator. A few months ago I was able to add Yubikey to such a configuration without a problem and in our Okta from the admin side no policies have changed.

Below I am uploading a screenshot at the moment when I want to add multiple MFAs on a user account e.g. Yubikey.

Interestingly, if I install Okta Verify on this computer, the system allows setting up multi MFA and this error is not present. On the other hand, when an employee logs into Okta with the help of Okta Verify MFA from his phone, it already rejects it.