Export Calendar buttons become inactive after pressing 'Export' (as file)

Site link ending in: /calendar/export.php?

To Reproduce:

1. From the dashboard, click 'Calendar'
2. Click 'Export Calendar'
3. Select any radio button for both "Events to export" and "Time period"
4. Click 'Export'
5. Save the file or cancel the save operation at the system level. Notice the same 'Export' button pressed is greyed out and unable to be clicked on - the page must be reloaded to change selections. This happens whether the file is saved or canceled.