Greetings from Syncfusion.
Query: I have a row already selected and click on another row, it does not select the new row. There are no rows selected.
We have analyzed your query and for your requirement, multiple type selection or checkbox selection has to be enabled to use the persistSelection property by default. So in the below sample, we have achieved your requirement by using the rowSelecting method of the grid to have only one row selected. Please refer to the below sample for your reference,
Please get back to us for further assistance.