Thank you @EliotBR for your interesting answer. That explains our trouble very well…
As far as we can tell now, auto_mode was turned on. We will test the manual mode as soon as possible and then I’ll share our results.
Do I understand you correctly that our data is not really reliable for an exact underground detection?
Would it be possible to change the value of the confidence in such a case? 100% confidence in our case is hard to believe with your explanation.