THC with Miller 625x

Just finished getting my XR all together and have a question about torch height control.

Plasma is a 2020 Miller 625. I have the two banana plug leads correctly attached inside miller . The torch fires correctly . When I run the thc test I get 0 volts at rest and 0 volts when active according to the test.

When I fire the torch from the manual button on screen the live voltage displayed on screen jumps to 6.3 briefly then shows 0.

The raw voltage on the two leads wired into plasma reads 186 volts when torch is active and polarity is correct. The plug running over to the control cabinet from the thc module is giving me a reading of .1 volts when torch is active and 0 when torch is off.

Any thoughts appreciated

THC Trouble shooting states raw voltage should be 60-150 v but I am getting a reading of 186

Control box is mounted on plastic isolators. I am using the included Usb cable and Usb isolator dongle along with ferrite chokes on each end.