CBass the "bypass" is a function of pressure. If the pressure is too high, it will get into the up pilot, moving the car. Great example for the guys that do not do much new construction, our TKE hydros can run at around 20-30 FPM with the valve coils completely unplugged, because this low pressure setting has not been completed yet.
I have seen this before, in Alaska, on a TAC 20 that was creeping while on viscosity. Give it a try and let me know if you need some help. It's a very straight forward adjustment, and the up leveling is also cake to dial back in.
