I have seen this behavior when you select a "Location" and have the settings (in the Apple settings for iBird not our app) set so Remember Location is ON. If this is the setting the state will always be included in the search and its easy to end up with 0 birds.
Also you should avoid picking a large set of attributes and then doing a search. If just one of the many is wrong you will end up with 0 results. So we recommend when doing a search that you start with one attribute and see how much it cuts the list down to. Then view the results before you pick a new attribute to include in the search. Make it step by step. Also be careful with the Any/Always switch in Color. For example if you pick Color = Orange AND Black the list will shrink drastically, while Orange OR Black it wont narrow as fast.
Mitch Waite
