freakouthtesquares Looks like we do just send the 0 discharge power and the Giv response acknowledges that it has been set, see below - but your Giv HY5.0 inverter still discharges somewhat.
As @johalareewi says, and I read similar things in Giv forums, some inverters are still discharging somewhat, despite discharge power being set to 0.
Our alternative approach to set SOC target to current SOC had a similar effect, which is why we switched away from that.
All in all, it's something that's unfortunately out of our control.