When the grid is put into edit mode, it creates its editors for each column field.
If the binding does not happen and the Kendo UI ComboBox blanks out, it is most likely that the value type of the column field does not match the expected value type by the widget.
For example, if the widget's dataValueField is a string but the column is a number. Here is a simple runnable example demonstrating the described behaviour. This is the only scenario that seems to reproduce the described ComboBox bank out:
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