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.