Fuzz face pedals behave exactly as yours is behaving. Fuzz needs to be maxed or close to maxed for them to do their thing. I suppose some people dig the fuzz knob lower, but that just isn’t the traditional way to use a fuzz face. Your pedal seems to be working normally.
Turn the volume up to 85-90%
Turn the fuzz up to 85-90%
Leave it alone and control your clean to fuzz sound with your volume knob on your guitar.
Its all there if you learn how to control it.
Glassy clean to overdrive to flat out screaming ...all with your guitar volume knob.
Sorry OP, my post definitely came across as snark. There's definitely plenty of that on TGP. As previously mentioned, just turn both knobs all the way up and control it with your guitars volume and tone knobs.