First Tip of Christmas
Leon Ashton-Leatherland - Troubleshooting Intune
My tip would be when troubleshooting an Intune issue the best place to focus initially is the user in question via the troubleshooting blade in the Microsoft Endpoint Manager admin center;
Navigate to Troubleshooting and Support > Troubleshoot
Click Select User to pick the user affected.
Now you have a customised view to show everything related to that user and from there you can drill down into the specific device or assignment affected.
Useful properties about the user account is also available in this view. This includes things such as; is the user even active, or have a valid Intune licence.