Sort does not work when not following a search

This is very strange. In the present Users UI module, you can do a search (e.g. type "a" in the search box to immediately narrow the set of User records displayed), then click on the headers of the result-list to re-sort them by full-name, username or email address. But if you click those same headings on the complete list of users that is displayed before you search, the whole Users app is wiped off the screen.