I have investigated the provided screenshots of the code snippets and I have noticed that you have configured the data source of the grid to be "Ajax", however, you attempt to make a server binding. This is due to the fact that a collection is returned via the view and then bound to the grid as follows:
However, this is an approach that is supported only with the ASP.NET MVC wrappers for the Kendo UI Grid. The ASP.NET Core framework, as a whole, works differently than the ASP.NET MVC and the server binding is not supported.
If you would like to continue with the Ajax approach, you might examine the example set in the following live demo:
Let me know in case any questions arise.
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