Interrapt G28

By selecting the value "All" from the 'Items per page'drop down list in the Webinars page,all of the created webinars are displayed,but the drop-down list disappears.

Precondition:
1.Click on the "Webinars"
2.Scroll down the page,and click on the'Items per page'drop-down list
3.Select the value"All"
4.Scroll to the bottom of the page to see the issue

Expected result:
All webinars should be displayed on the list,and the drop-down list should be displayed after each selection

Actual result:
All webinars are displayed on the page,but the drop-down list dissappears and user cannot choose a different value.