I'm currently trying to figure out exactly what counts as a prime engrams now. To progress Guardian rank from 5-6 I require 1 prime engram. However the OG prime engrams appears to have vanished from the game. Some engrams say they're primes but they don't progress, at this point I've had more exotic drops than prime drops. Can someone tell me if they still exist or am I doomed to be at rank 5 for eternity