Why can't I close a registrant's ticket details window?

When you click into a registrant's profile and then open the ticket details, once your are done, you used to click on the x to close out the ticket window and you were back in the registrants list.

Now when you click on the x, it does nothing. You are stuck in this window. You have to close the browser window and re-log in.

This has become such a cumbersome and time-wasting issue. Can you please take a look and repair?