Wiring neutral/ground when splitting panel for MultiPlus?

Well, per your previous (after hooking up the inverter dc side cabling only - ac side not yet connected) and with the battery voltage initially reading 6v then rapidly dropping to 1 or 2 volts within 10 seconds dropping, that seems like a whole bunch of current going somewhere??

How much current does the victron read when doing this, and does this only occur when you hook up to the dc bussbar ??...(just trying to isolate this a bit).