I figured out why I couldn't get the mummies to revive. Somehow, I either didn't install it or my game just completely messed up (probably the latter, because I reinstalled and most everything is fine). So now they revive when I hit them with a spell.
Now I have to ask, why and how? I don't understand how Larloch's Minor Drain has the power to completely heal undead flesh. Wouldn't it make much more sense to only be able to resurrect a mummy with a rod of resurrection (or some other raise dead spell). I understand the reason you can revive them is because these mummies are well preserved, but honestly, how many commoners are well preserved, and aren't they usually dead due to either an illness or old age? It's a neat component, but it really doesn't make much sense to me.