When attempting to use a verification code for Microsoft Multi-Factor Authentication (MFA) the Verify button does not appear to work and the UI appears non-responsive.

The HTTP response has the following error:

{
    "Success": false,
    "ResultValue": "PhoneAppOtpOathCodeCorrectButDeviceNotAllowed",
    "Message": "PhoneAppOtpOathCodeCorrectButDeviceNotAllowed",
    "AuthMethodId": "PhoneAppOTP",
    "ErrCode": 500121,
    "Retry": false,
    "FlowToken": “AQAB...kIAA",
    "Ctx": “rQQI...-Q81",
    "SessionId": "0066...edb8",
    "CorrelationId": "a31e...8014",
    "Timestamp": "2025-06-18T23:45:41Z",
    "Entropy": 0,
    "ReselectUIOption": 0,
    "ContinuationToken": null,
    "MobileAppAuthDetails": null
}

The Third-party software OATH tokens settings authentication method needs to be enabled.

From the Azure Portal:

- Select Entra ID
- Select Manage | Security
- Select Manage | Authentication methods
- Select Third-party software OATH tokens settings
- Select Enable
- Select All users
- Click Save