This started with EN Win 6.10. For some users, EN Win 6.11 seems to have corrected the problem. I continue to experience the issue in 6.11 on Win 7.
In "All Notes" context, when performing an intitle: search, the characters appear in the search bar (as normal) and then suddenly the 'focus' moves away from the search bar and any additional characters typed do not appear in the search bar. Rather, those characters end up as the title of a new note.