Andrew Sammut Thanks for the update and confirming the Hybrid Entra Join status of your non-persistent virtual desktops. The reason your users are still experiencing double authentication prompts for Outlook and Teams comes down to how the Primary Refresh Token interacts with your organization's Conditional Access policies. When a user logs into a Hybrid Entra Joined machine using just a standard Active Directory username and password, Windows successfully negotiates a Primary Refresh Token in the background. However, that specific token only carries a single-factor authentication claim because only a password was used to access the desktop.
When Outlook and Teams automatically launch, they silently present this single-factor token to Entra ID to access Exchange Online and SharePoint. Your Conditional Access policies intercept this request, recognize that the mandatory multi-factor authentication claim is missing from the token, and immediately force the interactive prompts to satisfy your security baseline. You can verify this exact state by opening a command prompt on an affected virtual desktop as the user and running the command dsregcmd /status to review the User State section. You will likely see that the Primary Refresh Token is present, but the MFA property is explicitly set to NO.
To eliminate these application-level prompts and achieve seamless single sign-on, the multi-factor authentication requirement must be satisfied at the very beginning of the session. You must inject an MFA claim into the Primary Refresh Token during the initial Windows desktop logon sequence. This is typically accomplished by implementing strong authentication methods at the lock screen, such as Windows Hello for Business or FIDO2 security keys. Alternatively, if you are using a federated environment, you can configure your infrastructure like Active Directory Federation Services to pass a valid MFA claim directly to Entra ID when the desktop session is first established.
VP