Copter detects RCInput when no RC connected

Hello.

We had an incident where the AP suddenly detected a PPM RCInput midway through the mission, even though the RC was not even with the pilot. Furthermore, the values it decoded were completely bogus, some of them being over 2000us.

Another oddity is that we use SBUS, not PPM, so I don’t know how it could have decoded a PPM signal.

I don’t know if this is a Pixhawk or Copter or RC receiver issue, though I suspect it’s likely the receiver. In any case, is there any way to detect and ignore this kind of event in the future? Could we force the Pixhawk to only listen to RC commands from SBUS?

Relevant image:

Log:

We use 2.4GHz X8R receivers along with the Q7 RC.

Thank you.