ERD diagram for all entities failing in Dynamics 365 - Error: Found an attribute with unrecognized required level

Question

I am trying to generate ERD for all entities in our Dynamics 365 instance using Microsoft Dynamics SDK Code through Visual Studios, but getting the following error:

System.ServiceModel.FaultException`1[Microsoft.Xrm.Sdk.OrganizationServiceFault]: Found an attribute with unrecognised required level. (Fault Detail is equal to Microsoft.Xrm.Sdk.OrganizationServiceFault).

Part of the code where failing:

 // Load the metadata.
   Console.WriteLine("Loading Metadata...");
   RetrieveAllEntitiesRequest request = new RetrieveAllEntitiesRequest()
   {
         EntityFilters = EntityFilters.Entity | EntityFilters.Attributes | EntityFilters.Relationships,
         RetrieveAsIfPublished = true,

  };
  RetrieveAllEntitiesResponse response = null;
  try
  {

 Error Point>   response = (RetrieveAllEntitiesResponse)_serviceProxy.Execute(request);
                builder._metadataResponse = response;
  }
  catch (Exception ex)
  {

  }

Please not that using RetrieveEntityResponse (for single entity) works, but does not show related entities in MS Visio diagram.

I have also used MetadataDiagramConsole.exe to run this for all entities, but it throws an error and SDK version is latest.

Thanks.