My "sell conventionals" button stops working sometimes, for reason I don't really understand. I'm staring at a stack of iron (among others), so there are certainly conventional materials to be sold. Is this a bug?
Also, is there any way to sell some but not all of a stack of materials? I just picked up a ton of exotics and would like to sell some of them, while holding on to a few in case they're needed for a quest or something (still playing; no spoilers!).