You could use the HiddenDataMember property in the Category cell and buffer the Name value in that cell. During OnEnterEditMode instead of looking up the value in the Name cell you could look up the value in the HiddenDataMember property.

Here is the snippet to use HiddenDataMember:

<ISWebGrid:WebGridColumn Bound="true" HiddenDataMember="Name" WebComboID="cboCategory" EditType="WebComboNET"
    Name="Category" DataMember="Category">
    <ValueList DataTextField="Type" DataValueField="ID"></ValueList>
</ISWebGrid:WebGridColumn>

The modified OnEnterEditMode event handler, I also modified this function so the process is only done upon entring Category cell:

function wgTest_EnterEditMode(controlId, tblName, editObject) {

    if (editObject.ToCellObject().Name == "Category") {

        var combo = editObject.element;
        var cellObj = editObject.ToCellObject();
        var nameVal = editObject.cellElement.getAttribute("Name");

        combo.SetAdditionalFilters("Name = '" + nameVal + "'");

        combo.SetText(cellObj.Text, true);
    }
    
    return true;
}

The secreenshot we are asking is the screenshot when the error occurs, this way we could determine on which line or on which function or property does the error occurs.

The dump file you attach is the ophuscated intersoft javascript. We could not determine the error without knowing on which function or property that caused the issue.

Regarding the difference between the file version and assembly version in the DLL our file also reported the same information as yours. You are already using the latest build of WebUI Framework. Please also make sure you already use the latest WebGrid 7 build, build 401 (ISNet.WebUI.WebGrid.dll and ISNet.WebUI.WebGrid.Resources.dll)

The OPTGROUP is used to grouped options in the SELECT HTML element and by default is not selectable. You could read more about OPTGROUP in this page

I am still discussing this issue with our developer, I will inform you if there is any update or progress regarding this issue. 

Our WebValueList is intended for per column scenario, the WebValueList property is available in the Column object not in the Row object. In your scenario, per row, the WebValueList will not be appropriate.

In your case, you will need to manually translate the value during initialize row event handler