This is an installation on our RV. Multiplus II 2 x 120 with BattleBorn batteries. Inverter runs fine. When plugged into shore power, it switches to mains just fine. When plugged into the onboard generator, power is rejected, presumably, as there is no indication of incoming power when in inverter mode. There is a clicking every 20 seconds or so, which I am guessing is the ground relay opening when trying to synch. If I switch to charging mode, the mains LED will flash. I just got the VE bus bluetooth module, in the hopes it would have some error codes, but I can't find this. The Victron Connect app shows AC in around 120V (like 122V) and frequency around 59-63 Hz. When starting the generator, it shows synchronizing (or something like that) up until the first clicking, and then just shows the AC in as above, with zero current. Switching between shore power and generator power is accomplished by plugging the shore power plug into the generator outlet. I thought I saw a caution to not use the vehicle 12v ground as the AC ground, and the generator was initially set up this way. I have tried disconnecting the generator ground entirely, and connecting ground and neutral together at the generator, but not connected to the chassis, all without success. I am guessing there is some neutral-ground issue that the Multiplus doesn't like, but I am hoping someone knows of some setting that I need to check.