This mod searches the game's list of ores registered to be generated during worldgen, so if the mod that adds lead handles it's own ore generation, mine won't find it. Could you tell me which mod adds the lead ore so I can look into the problem more?
Glad to help, These mods have these ores that are not shown my ore_info.
Technic uses as ores lead, uranium, chromium, zinc, sulphur, granite.
Elepower has it's own lead, nickle, viridisum, zinc, uranium ore.
Etheral mod also uses a few ores that are not shown. Etherium, bakedclay.