Range filter not showing correct products

[LeonKercmar]

I've created a custom property called "Operating Weight" and gave 3 products different values. The problem I'm having is that when I use the range filter it never returns me the product with lowest "Operating Weight". Example:

I've only changed the max operating weight slider. This should return me two products (product with the lowest value and the product between these two values) but it returns me only one (product between the min and max value)