Microsoft
MicrosoftLots of questions, I may not get them all answered, but hopefully this will help.
IndiaYankee , I'm glad you got it figured out. Scan source policies are the big key, but there are other Group Policies that you discovered that can also get in the way. The most important thing is that the device is enabled to scan for (driver) updates to Windows updates on the Internet, not via WSUS. So, that is the thing to be checking and working towards. The other recommendation is that you assign devices to the Driver policy about a day before you have the devices start to scan WU for driver updates... to ensure they are enrolled in driver management and don't get the drivers that are typically automatically deployed. Once all that is in place, then devices need to scan for updates, and it usually takes just a few hours, for the inventory to show up. That said, if devices were fully up to date before joining the policy, then there may not be any driver updates available.
Reporting then follows once drivers are approved. Drivers will show up in the selection list once we've received reporting events. The first few are from the service, and include Validation, Scheduling, and OfferReady. After that, to get further status, you need to have enabled the Data collection policy/setting in Intune (note: there is a temporary bug where the report points to Windows Health Monitoring, that is incorrect and will be resolved in the next Intune release this month). By enabling WIndows data collection, we are able to collect and process the client telemetry that shows devices downloading, installing, rebooting, and, most importantly, InstallSuccess, or Errors/Alerts when needed. The data collection requirements and steps are documented. You can start with https://aka.ms/IntuneDriverDocs
HTH, thanks for using Drivers!
-David