AH search worked differently before the UI change.
It would make new search, based on what was in the search bar, each time you changed category tabs.
So you could go:
1. Type "iron" in the search bar.
2. Dont press "enter".
3. Sellect "items" category.
4. It would authomatically search for everything "iron" within "items".
5. Delete iron and change it to "melchi".
6. Dont press "enter".
7. Sellect "refined resources".
8. It would search for everything "melchi" within "refined resources".
After the update, it wont do any searches before you press "enter" in the search bar.
After pressing "enter" it locks into w/e was there and will keep searching for it, regardless if you clear the search bar, change category or type something different. Till you press "enter" again.