Hi Paul,
Thanks for contacting Syncfusion support.
We would like to inform you that Editing feature is not supported when using RowTemplate feature in Grid.
RowTemplate feature is not compatible with all the features which are available in grid and it has only limited features support. We suggest you to refer the below documentation, here we have listed out the features which are not compatible with row template feature.
Please get back to us if you need further assistance.
Regards,
Rajapandiyan S