Hi David,
Thanks for contacting Syncfusion Support.
We have checked your code example and the reported problem due to you have not set the isPrimaryKey property for the Grid column. Because this property is necessary to perform Editing opertions in the Grid.
We have discussed this issue in our Syncfusion Knowledge base documentation. Please refer to the KB link:-
Please get back to us if you need any further assistance.
Regards,
Farveen sulthana T