Have you tried turning the O2 lever ON as per checklist/SOP but turning PASSENGER OXYGEN to OFF (instead of AUTO, AFM says AUTO or OFF if no pax)? At least one private Pilatus here they do that. This way crew quick donning masks always have oxygen, Emergency Descend procedure and QRH (if your sn has one) calls for PASSENGER OXYGEN to AUTO anyway.
Exec. interior (armrest masks) masks are permanently connected, and yes they do leak sometimes.