MOT_SAFE_DISARM = 1 disables ESC telemetry

I have a quad with a Kakute F7 and Tekko32 ESCs on Dshot150 with telemetry, running a recent 3.7 build. I’m using yaapu to display passthrough telemetry on an X10.

With MOT_SAFE_DISARM = 0, yaapu displays the battery cell voltage correctly all the time. With MOT_SAFE_DISARM = 1 yaapu displays the cell voltage while the aircraft is armed, and zero while disarmed.

Is this just the way ESCs work, or would it be possible to see the voltage while disarmed?