I also have a two PowerWall installation and I use some of the energy stored in the PowerWall to power my home through the night. As a result, the Sense never “sees the sun go down” during installation and doesn’t complete its signal check.
When I installed the Sense I disabled both the PV array and batteries at the “turn inverter off” stage and re-enabled them at the “turn on” stage.
Shortly after reaching out to Sense technical support (excellent) I set the backup reserve on the PWs to 100%. I don’t know if it was technical support or the PW reserve action but the signal check completed and the Sense began identifying devices.
My configuration is shown below:
