The rarity of echoing nightmare keys and primals have been mentionned… but is difficult to comment on… without some specific testing. If the issue only affects a “few” players… I’m sure you see the problem.
That being said… I’ve played 17h42m on Europe (solo gaming only, but seasonal (not SSF) hero) in an attempt to replicate the altar related issues… so far, I’ve failed to achieve that goal. I have gotten 4 nightmare keys and 2 primals (including the one for the first GRift 70). I have 590 paragons.