Some RBs - reading voltage problem

Hi,
I have RB Groove A-52HPn, ROS 6.40.4 and in winbox 3.11 it displays correct value of voltage.
However in console with command “/system health get voltage” it displays nothing (system displays no value from /system health variables). So it is not possible to write a voltage monitoring script.
Same problem I have on RB HEX r2 (6.40.4), and RB 493G (6.40.4).

On RB HEX v3 (6.38.3 and 6.40.5) it is working correctly.

Is it a bug in version 6.40.4 or something is set wrong? Thanks.

not all devices have the voltage monitoring chip.

I know, but in winbox it is correctly displaying the voltage. Only in console it displays nothing.

Hi, nobody from mikrotik cannot answer this? I can provide remote access to the device.

Did you try:
:put [/system health get voltage]