I examined the provided code. The reason for the described faulty behavior comes from the fact that the row template is not inside the relevant property.
If we use an implementation similar to the one below, the issue should be resolved:
"<tr data-uid='#: uid #'>" +
"<td class='checkbox'>" +
"<input type='checkbox' name='optCheck' />" +
"<td class='details'>" +
"<span class='name'>#: Name #</span>" +
"<span class='desc'>#: Description #</span>" +
Also, you could check our demo regarding the Row Templates - https://demos.telerik.com/aspnet-core/grid/rowtemplate
I hope the above information helps.
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