Phil,
My house bank charging path is twin #8 wires with manually controlled solenoids.
When I had flooded jars I got good charging. Once I moved to AGM telcom jars I found that after a day in the sun the house batteries would flow current to the engine and that I would only see charging when I put the system under a large load such as running the water heater on electric.
I thought that might be because I had a flooded marine battery (from 2005) for the starter. I finally replaced that in 2017 in the spring with a AGM. I still get almost no charging for the house bank.
I surmise the reason is because the telcom jars float at a higher number than the flooded units.