Unable to run the assessment or scan for windows updates on Custom images/Migrated images using Azure update manager.

The assessment/scan data shows no pending updates though we can manually run the updates from Windows updates on the client. Azure update manager is unable to fetch the assessment data from the Windows update client, is it because the servers we use are migrated/custom images? We do not see the Image publisher, SKU, or offer for all the migrated Azure VMs. Please suggest what options we have here as we want to use Azure update manager as the patching tool instead of SCCM after the migrations have been completed.

Thanks in advance.