While in Command, i noticed i was hearing a machine while the audio log wasn't displaying anything.
In the attached screenshot, the Quantum Router (the machine i was hearing) is the machine center-left.
When i got closer to it, the audio log finally picked it up.
It seems that i can hear the machine from farther away than the audio log thinks i can.
I added map notes in the attached screenshot for how far i could hear it from and where the audio log first picks it up.
Seed in case it's useful : EnergyPortableLog