You can use whatever primitive you need for the details template. On my end the read method is called with both string and int ID in the overload of the action controller (respectively, in the modal too).
Are there any JS errors in the console? Does the request is at least sent (i.e., appears in the NET tab of the browser's dev toolbar)? It is possible to be called but for some reason not accessible (e.g., server-side error).
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