I have same issue, no EC production for CANDLE and Solid Core Nuclear Engine.
I looked in cfg files, and found
upgradeTechReq = Thermal Electric Generator Mk2
I think it is weird, but don't know whether it is the reason. I tried to fix it, imitating other generator part working correctly, but didn't work.
And another question, the original alternatorPowerKW was 10 for CANDLE, and the replaced generator would produce much less EC. Maybe 0.04 to 0.08? Is it intended?