Hi! I can't reproduce this issue. I have tried with your modpack, as well as some of my own saves, and can make diamonds.
If it helps: I only enable diamonds in data.raw["furnace"]
and data.raw.["assembling-machine"]
entities with .energy_source == "electric"
, and a .crafting_categories
entry that matches "smelting"
.
I do this in data-final-fixes so if anything changes after this mod in data-final-fixes, I won't catch it.
Not sure if that helps, otherwise I might need an actual save file to investigate further.