Min FF on a jet does not occur at V min power, as on a jet FF changes with thrust instead of power like on a prop aircraft.
So min drag equals min thrust on any aircraft and min FF thus highest endurance on a jet.
Min FF on a prop equals min power required and does not coincide with Vmin drag/min thrust. Remember: Power required= drag * speed hence if your drag curve is "flat" chances are you will find yourself on the unstable side of the drag curve for min power i.e. increasing power on that side of the power curve doesn't necessecarily mean an increase in airspeed opposite to the other side of the drag/power curve where an increase in thrust/ will always lead to increasing airspeed.
Hope this helped