Sup with the decloaking deathclaws that muuurder me when I'm trying to farm Super Mutant Masters @ Black Mountain? This is too evil to be a bug.
I'm fairly sure that the only 'cloaked' enemies on Black Mountain would be the Nightkin. If I'm reading wrong, it may just be spillover from the Quarry. They're right next to each other, remember that the Quarry isn't just the area with the machines, it's a big area.