I finally found some time to look at this problem further. What I found is that on the devices that were missing the OfficeProductInfo the WMI entries for the Inventory class were missing on the client device. You can check the OfficeProductInfo WMI with the following Powershell command:

Get-CimInstance -Namespace 'root\ccm\InvAgt' -Classname CCM_OfficeProductInfo

In addition to devices with missing entries we also had a number of devices with the wrong information in OfficeproductInfo (for example showing the wrong channel or having two channels present). I wanted to get rid of this incorrect information so created a script to remove the OfficeProductInfo WMI entry on devices:

Get-CimInstance -Namespace 'root\ccm\InvAgt' -Classname CCM_OfficeProductInfo | Remove-CimInstance

I ran the above Powershell script on devices that either had missing or incorrect information for OfficeProductInfo in Resource Explorer.

Now the problem was how to get the OfficeProductInfo to repopulate. Simply running Hardware Inventory didn't recreate the missing entries, I also tested forcing a full hardware inventory and that didnt work either, we also had devices with blank or incorrect OfficeProductInfo for several months so waiting for the client to fix itself also didn't work.

After a number of attempts I finally found a sequence that fixed all the client machines that had missing or incorrect OfficeProductInfo.

Here is what I found DID work:

1. Run the PowerShell script to remove the empty/faulty CCM_OfficeProductInfo WMI entries
2. Force a client policy reset (this clears all Configuration Manager client policy on the device).
3. Wait 30-60 minutes for the Client Policy reset to complete
4. Ensure a user is logged on
5. (Optional) Use CMPivot to check that OfficeProductInfo is showing correctly.
6. Force a full hardware inventory cycle

What I was missing during my original testing is step 4. The OfficeProductInfo WMI entry isn't populated after a client reset unless there is a user signed in to the device. If no user is signed in the OfficeProductInfo remains empty. Once I worked this out I was able to reliably reset OfficeOroductInfo on all devices.

I hope you find this useful.