When on the same Surface (planet etc), it is generating no signal readings. but as soon as the player leaves the surface (on Spaceships or via cargo rocket) it starts properly outputting signals.
Effect observed with
PComb on Nauvis (main/starting planet), Player on Nauvis (not working)
PComb on Nauvis, player on Spaceship-in-transit (working)
PComb on Nauvis, player on Nauvis Orbit (working)
PComb on Nauvis Orbit, Player on Nauvis Orbit (not working)

Could you please provide a save game that can reproduce this bug?

I seem to be running into the same bug, It seems to have something to do with the surface creation/deletion of spaceships as i've seen the combinator break and resume while the player was standing still in nauvis orbit but automated ships were going.

Edit, https://imgur.com/a/ss0ZNo1
The Issue persists through a save/load and i have a save of it in both a broken and working state if needed

Looks to me like the spaceship is consuming/producing more than the given scale can handle.
The FAQ states in this case:

If the output values are over the scale of 2³¹ then the combinator output doesn't update the stats. In this case please set the scaling factor to a reasonable value.

the power combinator in the video appears to have a scaling factor of 6, meaning the ship would need to be producing around 2 quadrillion watts. space ex scales up quite a bit, but i don't think that one is going that hard

i suspect this is related to this other SE issue: https://mods.factorio.com/mod/power-combinator/discussion/632cb8ceab7353a59a7a6c16

i've also been able to reproduce it with a ship that generates like, 13mw at best

1 https://i.imgur.com/pV4XpGy.png 2 https://i.imgur.com/y926gtl.png 3 https://i.imgur.com/GxtZR5K.png

here's the savegame: https://www.dropbox.com/scl/fi/eopd43irk7wdxenuw3y1c/SpaceEx-K2-10-SPM-23a.zip?rlkey=d5riw6pfa0ue8u7689251pva5&dl=1

it has a mod you won't have, PARM, but you can ignore that