Several owners reported that these machines are not grounded well and this is a potential safety hazard.
This seems to be one of the issues addressed, or at least partially address, in the “2020 New version.” I tested the grounding and it seems to be grounded. Inspecting the screw holes, there is still some residue that may prevent the best possible grounding, but there seems to be enough raw metal exposed to make an electrical connection between the different chassis parts.
Use your multimeter or a continuity tester to check your machine. You can watch Seon's video on checking and correcting this issue: