I am facing the same issue where, if tapping outside the selected range on the bar, the whole range gets shifted across to the tap location. Depending on the location and size of the bar on the screen, it is quite easy to inadvertently do this and lose the slider values.
While it is not officially supported by version 2.3.1, I found that removing the binding of touchstart and mousedown events to the range line did the trick.
https://github.com/IonDen/ion.rangeSlider/blob/2.3.1/js/ion.rangeSlider.js#L686#L687
A more generic approach could be to create a new config parameter named something like disable_line_touch with a default value of false, and only skip the above binding if its value is set to true.