Incoherent behaviour in geolocation based search


I run into a puzzling problem performing an API call like this one:,LNG,1mi&until=2014-08-04

where LAT and LNG are valid values for latitude and longitude.
With some particular choices of values (I can give you the exact values in private if you need context) the search for the second page of results returns 0 values, while with different values just a few meters away the search returns hundreds of values.

To get the next page of results I tried both using the next_results field in the response boy and setting the max_id parameter to the leat id in the first page of results.