And shore power does not connect through that isolator, as is visible from your wiring diagram as well. Shore power / battery charger (E) has separate outputs for start and house batteries, and those are connected directly to the battery banks.
You should check if your battery charger gets power, e.g. any lights on? If not, find the fuse box between the shore power cable and your battery charger (not visible in this diagram, as it’s in the 230V diagram). Could be that the circuit breaker or the residual current device has tripped. On 375GL, that box is found at the left aft corder, accessible through the on-deck lockers.