I hard coded the select content where in my “real” application it makes a roundtrip to the server but you can see the effect: Missing borders when you add a row.
You need to click on the locations tab first and then back to “Employee Time Cards” tab to render the grid.
I see this. The problem is in formatter:'select'. The value returned from formatter is empty string which causes the cells not to have borders. Also will see how to fix this.