George duffy

I know but I'm wanting to know why it's not picking the low b up even when plugged in

I'm currently setting up a bass in drop b and for some reason the tuner isn't picking up the low b even when plugged in and not using the clip on mic, it works fine otherwise but just will not register the low b, does anyone know why this is and how to fix it? (I can't just tune to the 12th fret harmonic because I'm currently trying to set up the intonation)