Xamarin.iOS HitTestAtX always matching for all of the series

We have a graph surface with some point markers on it and we want to show a custom tooltip every time the user taps on a point marker. So far I’ve used a UITapGestureRecognizer, convert the touchpoint in the chart frame and for each of the renderable series perform a HitTestAtX with a radius (I’ve tried 1, 5 and 30) but it always returns true, even if I tap on an area where there’s a gap in the chart. Here’s some sample code:

SCIHitTestInfo hitTestInfo = renderableSeries.HitTestProvider.HitTestInterpolateModeAtX(touchPoint.X, touchPoint.Y, 30, renderableSeries.CurrentRenderPassData);

if (hitTestInfo.match)
{
       Console.WriteLine($"Tapped {hitTestInfo.xValue} {hitTestInfo.yValue} with index {hitTestInfo.index} of the series {renderableSeries.DataSeries.SeriesName}");

       var elementSeries = Model.BottomRightLegendList.FirstOrDefault(tup => tup.DataSeries.SeriesName == renderableSeries.DataSeries.SeriesName);

       var element = elementSeries.GraphElement;

       if (element != null)
       {
            matchedElements.Add(element);
       }
}

Why is the “match” property always true, even if there are no Point Markers in the radius?