Hi, I play in 1.12.2 and, as the title says, the ores aren't spawning, I have both Base and Modern Metals, MMDLib and Orespawn, It hasn't happened before with the same modpack I have now. Could anyone help me?

There are a few really long-standing issues that we've never been able to track down due to a lack of ability to reliably reproduce them or find the actual cause. We might have a build that fixes things on our Maven if it hasn't (yet) been pushed to CurseForge.