I just finished adding the ability to search different categories and I noticed something strange. I typed “Bird Spotter” and searched in the different categories and I noticed that the All and Music categories gave the same results (1 song). But the Software category gave multiple results including an app named Bird Spotter. It seems odd to me that the app Bird Spotter would not show up in the All category. Why doesn’t it?
Try the query by hand in your web browser and see what sort of results it returns. If this is different somehow to what the app shows, then there’s a bug in the app somewhere.
However, if the results are the same then it’s just the way Apple is providing these search results to us. In that case you’d have to ask Apple why. 