After inspecting the provided project it appears that there is some invalid configuration in the editor template for the Grid - all editors are strongly type (EditorFor helper is used) and at the same time the "Name" option of the widget is specified which is invalid configuration.
<label> Employee: </label>
@(Html.Kendo().DropDownListFor(i => i.Employee)
Also the from the provided information it seems that there is no default value set for the "SelectedCustomers" field which can prevent the MultiSelect from working correctly - could you please set the DefaultValue to empty array and let us know of the result?
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