I came across this "exploit" like three minutes ago. We were in hellfire ramparts, with my alt, 64 level warlock, helping a friend.
When we were done, i left group, and when timer that was going to port me to Shattrath went to 4 second, i starting DE the items i got so far. But i was teleported to shatt before i successfully disenchant the item, and by surprise, i saw into my inventory that there was no cloak nor any shard.
its kinda useless, but its an exploit nontheless