I took the trouble to do a series of downloads just to compare values. I'll download some of those pictures but need to do a detailed schedule of results. Note that the values remain negative - proof of infinite co-efficient of performance and our resistor is dissipating plus/minus 6 watts in temperature. Just out of interest that beautiful waveform entirely disappears at below 36 volts from the supply.
CHANNEL 1 shunt @ 0.25 Ohm
CHANNEL 2 battery
CHANNEL 3 gate
CHANNEL 4 math trace product of channel 1 and 2