Modelling an existing database in .NET Core 2.x

Question

I have an existing application. I am trying to port some pieces over from .NET 4.x over to .NET Core. I have created a context in my .NET Core app. I have create a db context via scaffold-dbcontext. I can run a basic query (hooray). Life is good. Now, I want to add in some async queries. I get the following error:

System.InvalidOperationException: 'The provider for the source IQueryable doesn't implement IDbAsyncQueryProvider. Only providers that implement IDbAsyncQueryProvider can be used for Entity Framework asynchronous operations. For more details see http://go.microsoft.com/fwlink/?LinkId=287068.'

code:

var ctx = new GolfGameContext();    
var userId = await (from u in ctx.AspNetUsers where u.Token == UserToken select u.Id).SingleAsync();    
return userId;

This error seems strange. I have created some .NET Core 2.x apps from scratch and everything seems to work properly. I am able to do async queries with them just fine. When I look at the error link, I get taken to information about EF 6.x. I am guessing that there is something that the scaffold-dbcontext puts in the resulting models that cause this problem. I am also guessing that the code I have created in Core 2.x doesn't contain these same limitations. Am I on the right track? Do I need to change something in my context/models to get async to work properly? All thoughts are welcome.

TIA,

Wally