Upgraded from RC5 to RC7 today, along with the new COFH-Core / etc. All dependencies met.

Reactor seemed fine initially, but decided to upgrade the Ender IO conduit connected to it from the 5kRF to the 20kRF version. Upon replacing the cable, the indicator light on the reactor power tap would stay red

Played about in a new single player world, creating a simple 3x3x3 reactor to test. Had the same issue. Rolling back to RC5 fixes the problem.

Full results:
RC5 - connecting cable: Tap activates (light green), power flows
RC7 - after mod upgrade: Tap still functional (light green), power flows
RC7 - after replacing cable connected to tap - Fail, light stays red, no power flows

Rolled back to RC5 for now, but thought I should report it.

Looks like #316 is the same issue. Apologies, the issue wasn't reported when I started writing this.

so, looks like maybe the power tap is not recognizing the energy node, TE4 cells, or cables on forming by reading your issue. Good to know it is not just the other stuff.

Found it. I'll roll out an rc8 soon.

Seems so. I tested every power conduit type I could think of, and none seemed to work if placed after installing RC7. On RC5 everything is fine, as are untouched cables after the upgrade to RC7. It's very odd.

Investigating this now; I'm rather surprised at this, as that code hasn't changed.