Extended Range - How exactly to detect C1?

Guitar Low E doped to C1
This tutorial shows MIDI BASS 2 detecting C1 note.
Overcoming the low end range restriction of MIDI Guitar 2 with GP
GigPerformer Forum

In my test, MB2 - Never detected lower than D1.
however, MG2 Mono DID detect C1

which is correct?
C1 = (MIDI note24)
C1 = (MIDI note 36)
C2 = (MIDI note 36)