Apply/GroupBy/Aggregate in .NET 5 / Odata v8preview3 / EFCore 5 doesn't work

Hello,

I have problems with Apply/GroupBy/Aggregate in .NET 5 / Odata v8preview3 / EFCore 5.

I'm not able to use simple expression like $apply=aggregate($count as OrderCount).

I receive the following error:

System.InvalidOperationException: Processing of the LINQ expression 'GroupByShaperExpression:
      KeySelector: new NoGroupByWrapper(),
      ElementSelector:EntityShaperExpression:
          EntityType: OperationExecution
          ValueBufferExpression:
              ProjectionBindingExpression: EmptyProjectionMember
          IsNullable: False
      ' by 'RelationalProjectionBindingExpressionVisitor' failed. 
This may indicate either a bug or a limitation in Entity Framework. 

Can you help me to resolve this problem?

Obviously for me, it's not a solution to use ToList() and aggregate client side.

Thanks

Fabio

Start by reproducing $apply=aggregate($count as OrderCount) with .NET 5, ASP.NET Core OData v8preview3, and EF Core 5, then inspect where the GroupByShaperExpression reaches EF Core's relational projection handling. Done means server-side aggregation works without ToList() or client-side processing, with the reported exception no longer occurring.