Ember not routing from front-end to JSON API back-end

I am new to Ember and am unable to diagnose a 404 HTTP Error between the Ember front-end and a .NET Core 2.1 JSON web API. Can someone please help?

I have posted a link on Stack Overflow that contains the details:

If you just want to get some more attention to your stackoverflow question, please use the ember community slack. Crossposting here and on stackoverflow is spam IMO.

OK. I have posted there. Thanks.