Not sure if this is really a bug, but wanted to post in case it was.

Short version, a warded glass roof apparently interferes with the rift monitor block.

Long version,
the monitors were working for the longest time, however I got tired of being rained on while tending to my rift.
I put a roof overhead with the warded glass.
I noticed the monitors started having issues tracking the rift.
I tried toggling them to resync, and that seems to work intermittently.

For reference the rift is -99 89 -1239
the monitors were -99 76 -1242 and -98 76 -1236

If it is a range issue, perhaps the range can be expressed as relative range compared to the runic matrix in a future update to add context?

Figured out how to recreate
If you completely unload the chunk such as going really far or into the nether, then on chunk load the montors work.
When traveling just far enough for the chunk to not load things like entities, but still be within lazy loading distance, then the monitors appear to not have a rift, though output seems locked at the state the monitor was at when it switched to lazy load.

Also realize I massively over-engineered the size watching, comparitor into relay, set relay in to 14-15 as preferred, then invert with redstone torch to keep device off until above threshold

updated safety circuit

• Purpose:
  • if rift detection lost, do not enable connected device,
  • else if rift detected and output above threshhold (in this case 14) then enable rift draining device

Further analysis:
this might be as described in the book, the changing size from outputs 15-14-15 again might be what caused the monitors to lose focus.

For items like this, would it be good to add to the wiki?
Would wiki entries add or subtract from the mod experience? (asking as I've done technical documentation, not so good at thematic stuff, but thought this might be another way people can support the project)

This confuses me, shouldn't this be close enough?
for context they were here a while now, but I've left far enough to unload and reload the location

So is the issue here it not reconnecting when the chunk the rift is in loads some time after the monitor gets loaded? Or is it the output being locked at what it was even though the monitor has no rift?

For items like this, would it be good to add to the wiki?

I'm not necessarily against it. I spent most of my documentation time on making the ingame entries better since that is what 99% of people will be using, and keeping the wiki for mostly technical stuff, but I guess it could also be useful as a "cheat sheet" for this kind of thing. I tried to give more qualitative descriptions in the book instead of hard numbers to encourage experimentation, but of course the mod is open source so people can find out the numbers if they really want to.

I think the more critical issue is the output getting locked.
It seems to recover if you toggle the rift display to force an update, but if you have machines dependent on the output then you could end up with rifts getting harmed.