After being under siege for a while from a necromancer, I figured I should at least look for some metal ores lest my imports stop coming in. I have 4 miners (from what DF tells me), and none of them look like they want to work. The mining designations are definitely pathable (one of them extends the main stairwell), and they don't appear to be holding anything foreign in their hands, so I'm not sure what's going on.