The Harmonic Minor scale has in comparison to the Natural Minor scale no Minor seventh but instead a Major seventh. The Natural Minor scale has a whole note step between the seventh and eighth degree and without the lead tone the gravitating effect towards the root note is missing.
The Gipsy-Minor scale is a variation of the Harmonic Minor scale and contains an additional lead tone to the dominant. (The Gipsy-Minor scale is not listed on the ScaleTwister)
F- Minor-Harmonic (Root not of the chord + Fourth)