BigReactors-0.4.0rc8 water coolant, no RF generation, 2 coolants one in, one out.

Tested on creative world, 3x3 works, 7x7 works, 5x5 does not produce RF

Please provide screenshots of your faulty reactor. Reactors with coolant ports aren't supposed to generate RF directly - they produce steam, which you have to convert to RF.

Retested and yes, the coolant ports were to blame, however I had to actually completely destroy the whole multiblock structure and rebuilding it somewhere else, not sure why.

All right, well, reactors aren't intended to produce RF when they have coolant ports installed. That's by design.