Minecraft version & Mod Version:
MC 1.16.5, SSN 1.3.5

Single player or Server:
Both (first discovered on a multiplayer server, after which tested in singleplayer world and gotten the same result)

Describe problem (what you were doing / what happened):

Pretty simple solution to keeping furnaces fully stocked with fuel right?
Well it seems that by doing so, the second and third furnaces from the ground are NOT stocked with coal.

Well, what's going on then?

Hmm, interesting, I'm able to export coal into places where they normally wouldn't belong.

Just found it funny on my end, because then it allows me to do this:

Which I'm pretty sure isn't intended. (Yes, I'm able to see the speed upgrade that's inside the cable. There are no additional blocks apart from the export and link cables, a root and a storage request table.)

There should be either a blacklist on what the cables can connect to, or a better way to fine-tune which block the export cables are targeting.

Same goes for the filtered import cables, which decided to target themselves rather than the furnaces:

Crash log (if any):
None.