They may have had a sudden increase in being hunted since the suction cup dropped and has a sales thread going.
More hunted may mean fewer drops given out of the bones. Could also be that MA turned the DNA part drop off for a while until that suction cup part sells. Then loads of DNA parts may start to drop after.
Out of curiosity I did the full "500 fouls" mission today at Eos (didn't touch them for months after finishing the "100"). Loot was ok, plenty of muscle oil, but not a single bone