Any specific power plan or battery limits enable? Try to temporarily disable them. Remove the cable between SBV and HuB, try to enable the paralel switch withouth the hub, if OK disable and connect the cable at the SBV side but removed from HUB, try to enable again. If OK, disable switch, connect the cable and the HUB (but nothing connected to the HUB(no panels no inverter)....step by step till you find a blocking point. Do not connect or disconnect the hub on the SBV with the paralel switch enabled!!!(it should always be in disabled when connecting or disconnecting)