The Creative Flux Capacitor generated by the crafting recipe has an NBT tag Energy:0, whereas it should be Energy:250000000 (that's 250 million). With the current energy value, TE thinks the capacitor is empty and won't let it turn on. There's no way to charge it to fix the value either, since creative flux caps have an immutable energy value.

Currently the only workaround is to cheat in one from JEI or the creative inventory that has the right NBT tag on it.

We need to make sure that we create this item with the appropriate tag, and that any recipes requiring this capacitor function properly after adding the new NBT tag (probably just mark them to ignore NBT entirely since this is one the few TE items delineated with metadata rather than NBT).