@Melissa1863
Congratulations you are experiencing the consequences of Airbnb's Summer Release! *sarcasm
I can tell you before the summer release, it would not have anything to do with the number of houses in the same location. ALL listings would have shown up.
Airbnb has screwed up the search function and it is no longer user-friendly for guests or hosts. If you peruse the forums here, you'll see you are not alone, and there's probably nothing you can do, unfortunately.