Compact THC 150 - problem with plasma cutting of sheet metal

Hello.
Voltage measurement value on the THC 150 screen changes. In the Mach3 torch control interface, the torch changes height. However, this is practically imperceptible to the user and when the torch is too close to the sheet metal, it shuts down.
All outputs (ARC, DWN, UP) are connected to the AXBB-E isolated inputs together with the power pins. The measurement terminals marked 'Plasma Voltage' on the chassis are connected to the electrode, material and plasma source. I am using Mach3 software with the AXBB-E plugin installed.
What else needs to be tweaked in the controller, material position or Mach3 for it to cut without problems?

Sounds like a leak to me (interference perhaps?), check all your earth (ground) wires are secure, make sure no control and power wires are in close proximity to each other...

Plasma machines are notorious for needing a good solid earth/grounding electrically they're super noisy. Hopefully someone else has a better input for you :)