I encountered this on my server; if you leave a remote thermal monitor running and leave the area (so it unloads) and reload the area, it will stop receiving power. I removed the monitor and the wires are still acting as if they are connecting to the area the monitor once was. Also, if I try to place any other machine there it will not receive power either.

EDIT: Another note, once the server restarted the "corrupted invisible block" disappeared, in that a wire no longer appeared to connect to the invisible area. The area was able to receive power again.

Which mods/versions?

Well, as per the changelog, since this might of been fixed of already. Try testing it with the latest version.

http://ftbwiki.org/Feed_The_Beast_Infinity_Evolved

Version 2.3.4a

I tested it a few times with this version and the latest. However, I can't really test it with the latest version on the server because I don't own the server.

2.3.4a:
Singleplayer works fine. TPed away and to the remote thermal monitor. Still received power.
Mulitplayer results in the bug described in the first post.

Latest:
Singleplayer works fine.
Can't test in multiplayer as I don't know the exact setup of plugins on the server to emulate the conditions.

I don't necessarily think the bug is game-crippling though, as the server can either restart or the bug in the version can be bypassed with immersive engineering coils.

Meh, I need to bug the FTB core team to maintain their most used pack >.>

I have the same issue in Version 2.4.3a.
@xbony2 Can you please fix this bug.
My Nuclear Reactor just exploded, because the Remote Thermal Monitor didnt had energy.
I am using Minecraft 1.7.10

Sorry but Nuclear Control 2 is basically discontinued. The last time we pushed was in 2017 and we probably won't again.