Problem solved!
The issue is with the configuration of the AC Current Sensor Assistant. When asked to set the location of the PV inverter, I chose “PV inverter coupled on AC input 1 of this phase” because my PV inverter is connected to AC-In-1 along with all the other AC loads (grid parallel mode). Nothing is connected to the AC outputs.
In this configuration, the system should calculate AC loads power as GRID + PV + INVERTER but it doesn’t. It fails to add on the PV power to the AC Loads power.
It also (strangely) subtracts the PV power value from the grid power value (but only on the VRM, the GUI shows grid power fine??). All very confusing!
Anyway, the “fix” was to re-run the Current Sensor Assistant and set the PV Inverter location to “PV inverter on output of this phase” which is technically incorrect but the system now treats the PV inverter as supplementing the AC loads and so the correct AC Load value is displayed.
In this configuration the Grid Power in the VRM is also correct. This appears to be a bug that I hope will be resolved in the future.