When exporting to Excel (and PDF) the "busy" symbol, the circle of dots, is shown, and where it disappears after exporting to PDF, it stays after exporting to Excel. Regardless of whether one chose Open, Save, Save as or even cancels the operation.
When returning to the browser, e.g. after closing Excel, the page is frozen and no controls react. The browser is alive and a Refresh works, and after accepting the data is sent again, the screen and grid reappears. and everything is active again.