Although this is a pretty old issue, I thought I’d add what happened to me…. the probe was working fine until I realized I was getting shocked by my ungrounded Chinese spindle. Once I grounded that, the touch plate started running in reverse. I found out that I had wired my touch plate backwards so it was applying the 3.3 volts to the bit, closing the switch so it was always closed after I grounded my spindle. After I reversed the wires on my touch plate, so the clamp was ground along with the spindle, things started working as expected again. Hope this helps someone.
