I played around with this a little more today. It works fine on an iPhone, allowing the user to select any distance. On the iPad, the minimum allowable selection was 1000 sm, and it offered increasing selections up to 10,000 sm! But, if you just make a swipe down and don't select anything, and then back out, you'll discover that the filter distance has been reduced. Try it again and the distance is further reduced. I did this a few times and got it right where I wanted. It appears that there is a bug in the iPad version. But swiping blindly several times seems to get the desired result!