I deleted the post because, just as you said it seems plausible that in a test sequence the cancelling of the magnetic field is desirable and aditionally it could not explain the low voltage drop at R30.
You could also check the current limit of Q3 (IRF9Z24). To my understanding this MOSFET is applied as current limiter (constant current source). If you can’t get enough current through R30 it may be too much limited, the voltage ramp (red) shows the open-circuit voltage, to my understanding there should always be around 9V at Q1, when not switched on. It seems that you may are at the very beginning of the characteristic curve when you not even have enough current to get the 9V on Q1.
This is also exactly what you see at the very end of the test sequence, where the red curve does stay at the 9V. That the current does increase slightly at the end could have some cause in any capacitance or inductance of the circuit.
Hope this helps more.