Electro magnetic flow meter fluctuations

I have a honey well electro magnetic flow meter for brine controlled by a masoneilon 31000 series globe valve.

the meter gives a stable reading when the control valve is opened anywhere from 0-10% but opening the control valve any further causes the flow measurement to fluctuate wildly, sometimes full scale fluctuations.

I have simulated 4-20mA and I get a stable reading with no fluctuation at all.

the flow at the end of the run is a constant steady flow

I’ve done a bench test using water and the flow meter worked perfectly

I’ve installed grounding rings as the pipe is pfa lined through the whole circuit and it didn’t fix it( the pipe section of the flow meter is pp lined with hastelloy electrodes)

the flow meter doesn’t fluctuate when there is no flow , it stays on 0kg/hr which is good

I’ve noticed when looking at the measured values while in the parameters that the measured conductivity fluctuates a lot , 5000-20,000 us/cm every couple seconds. I would think the conductivity should stay the same as the liquid is being pumped in a loop and isn’t changing or mixing at all

I’ve had a vortex analog flow meter in series with The electro magnetic flow meter and the vortex meter gives a stable reading whereas the magnetic one fluctuates a lot

Ive attatched a pdf of the parameters and highlighted the changes ive made, is there something im missing?
FIT-108 Honeywell Changed parameters.pdf (188.4 KB)

How close is the flowmeter to the valve? ≥3D?

Is the flowmeter installed in front of the valve?

Flow meter is 300mm in front of valve.

pipe size is 1 inch

Contact the manufacturer. Something doesn’t seem correct with the meter.