Additional meeting and call-related features and issues within Microsoft Teams for business
Dear ARF94,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
Based on your description, it seems that you are trying to using PowerShell scripts to change a users Teams calling policy to revert to a different one. For issues with PowerShell, we have the dedicated communities that has abundant experience with PowerShell command scripts, we strongly suggest you post this question in PowerShell community support resources - PowerShell | Microsoft Docs. Experts there might be available to tell you why this worked before but not it does not work now and provide relevant suggestions and solutions of PowerShell commands to let you know how to make this works again.
Hopefully it works for you.
Sincerely,
Tommy | Microsoft Community Moderator
***Note: In the event that you're unable to reply to this thread, please ensure that your Email address is verified in the Community Website by clicking on Your Account Name > "My Profile" > "Edit Profile" > Add your Email Address > tick "Receive email notifications" checkbox > click on "Save".***