You are probaly right even if with the scope it's not very clear. After grounding everything, changing the power supply, i tried to find a software improvement adding a timer but up to now it's not 100 % working. A g38 choosen without error code was looking like an answer :o)
With 2.5.1, with 2 different controlers , I want to use the G38.2 or the G38.3 G-code to set the zero of my machines.
The movement and touching detection is OK BUT I have sometime (more than 50%) an error message just when contacts saying me that the probe trips during a non-probe MDI command. But the G38 is a probe MDI command I think ?!??.