Confusing behaviour 48/5000 Quattro-II on GridSet Point 0 (300-400W) - Overload L3 Warning?

Hello,
we have installed a new 48/5000 Quattro ESS System, New Firmware on all Devices and latest Cerbo GX Version, ESS assistant is running on all devices - config checked…
after the PV Production was going down today i discovered a confusing behaviour… on GRID Setpoint 0 i always have a consumption from grid… around 300W

after that i changed my grid setpoint to 5000W and -5000W L3 stays always the same? any idea? looks for the the 3rd quattro is on passthrough or something like that!

Overload L3 Warning?