Microsoft 365 Device Based Licensing not working

We cannot get Microsoft's 365 Device Based Licensing to work.

1. We have the DBA license in Admin Center > Billing > Licenses.

2. We have created an Azure AD group, assigned the license to the group, and put hybrid joined devices into the group.

3. We have added the regkey HKLM\SOFTWARE\Microsoft\Office\ClickToRun\Configuration > O365ProPlusRetail.DeviceBasedLicensing (with a value of 1) onto the devices

4. We have run the ospp.vbs status to make sure no Office key exists.

5. We have run OLicenseCleanup.vbs to reset the 365 activation state.

But, still the installed Office365 will not activate to ":this device" and continues to prompt for an Office365 user to sign in to their account.

Any help would be greatly appreciated?

Mat