Go to, for example, the add group members page. The follow details are wrong (they used to work).
1. To expand the search options, you have to click on the triangle icon. I think clicking anywhere on the 'Search options' text should cause these to expand.
2. If only one user matches the search, select them automatically does not work.
3. Keep selected users, even if they no longer match the search sort-of works, but displays the selected users twice if they do match the search.
Sam, will you be able to take a look at this? If not, shunt it back to moodle.com.
See http://moodle.org/mod/forum/discuss.php?d=168568 for someone who actually wants this to work.