How to get specific selection of checkbox from a popup datatable in Webix?

I have a popup data table in each row of a maintable with some checkboxes in it. I am selecting/checking items randomly by clicking the checkbox buttons for each row and printing the values checked with the help of Print button.

I am observing that only the last selection of checkbox buttons are overwriting all the earlier selections.

How can I get the appropriate selection of checkbox buttons corresponding to each row?

Snippet: https://snippet.webix.com/11irkt7o

Thanks.