Strange reading on 301 panel

[JOHN SLEIGHT]

I have a B45 of 2011 vintage. It has 3 sets of batteries: Service, Starter, BowThruster.
Generally when in the marina on shore power the isolators for the starter and bow thruster batteries are switched off. I leave the service battery switched on as this runs the fridge and freezer.
Recently I noticed that on the 301 panel it displayed that the starter battery was at 1.1volts. However on the shore power inverter it displayed all the batteries as 14.1volts. When I switched on the starter battery isolator the engine starts immediately and the 301 panel display goes to 14.1 volts or thereabouts. I am puzzled why I am getting this weird reading of 1.1volts....has anybody seen the same?

[diverphil]

I have noticed on ours the battery voltage is not shown unless the isolator is on, so with the shore power connected and the house bank on it will show full charge on house but nothing on engine, if I then switch engine isolator on that also then reads full charge. I assume the volt meter is wired including the isolator in the circuit and wont show anything unless the relevant circuit is on at the isolator