When the option 'Unlock double furnaces through research' is disabled in the mod settings, the double-iron recipe is missing, allowing you to place the furnace but preventing it from working.
Please update technology.lua to fix this."
technology.lua
else
table.insert(data.raw.technology["advanced-material-processing"].effects, { type = "unlock-recipe", recipe = "double-steel-furnace" })
table.insert(data.raw.technology["advanced-material-processing"].effects, { type = "unlock-recipe", recipe = "double-iron" }) --This is missing.
table.insert(data.raw.technology["advanced-material-processing-2"].effects, { type = "unlock-recipe", recipe = "double-electric-furnace" })
end
（English is not my native language, so I'm using Google Translate. I hope you can understand.）
