I don't know about hybrid organs never working - but there are problems, not least the tuning. Even adding temperature compensation to the digital ranks to adjust the tuning isn't 100% accurate - the problem being where to measure the temperature - incoming air, building ambient, inside the swell box and so on. It seems no one solution is possible.
A couple of the tracks on my You Tube channel (the "Fugue on Deux Themes ..." is one) were recorded on the hybrid organ in st Peter, Addingham here in West Yorkshire. That works pretty well - but the tuning usually has to be tweaked manually to get it spot on.