Multi RS: Passthru - PV charger doesn't charge

After sunset I switched to "passhtru" for the night, living the battery at about 40% of 10kWh. I don't like "ON" state, when at low battery it recharge using ACIN power. And doing it in short periods, like 1...3 min. :(

After sunrise I was expecting the battery to be charged using PV charger, but it didn't:

Swithing to "ON" state, the PV charger started to work well:

In the manual the following can be found:

PASS THROUGH

This mode closes the AC input relay and passes through AC voltage from the AC input to the AC output while the inverter/charger remains off.

The solar charger remains active.

Does the "remains" mean that it has to be active before, or it is a bug?

(The passthru mode is important for me, because in this mode I can be sure that there is no power feedback to ACIN. For safety reasons the grid service provider's power meter can detect feedback, and a GSM module pass the alarm to their control center... (fine, investigation, etc.)

Therefore I use ON function ACIN disconnected as far as possible.)