I'm making a smelting array of mixed-metal furnaces that change recipes based on supply. Nitinol and Copper-Tungsten recipes do not set the furnaces, and there is no custom recipe in the added tab.
Sorry for the late reply, I just tested this and I seem to be able to set both nitinol and copper-tungsten simply by using the item signals. If you are sure it doesn't work for you, send me your mod list and ideally a save or a blueprint of the setup and I'll take a look.
