If I go to a collection, and click edit and search for new members
e.g.
http://en.m.wikipedia.beta.wmflabs.org/wiki/Special:Gather/by/Jdlrobson/5#/collection/edit/5
when i type goobledegook the search returns no results but the UI does not reflect this.
This could be a solution right now.
Try another search is a button which when clicked clears input.
Our empty screens for all search pages (desktop and mobile) are pretty awful. Maybe the Search team will take a look at fixing that in the future :)