I hope for those who ran elite raids with full groups and got nothing that you bug reported it because even if it is not a bug they need the data to determine if the game is actually increasing the chances with the increased difficulty from normal to elite. That could be where the bug is if it exists and you could still be only getting the 1 in 6 chance even on elite.
I would definitely advise the player who made 20 completions and did not get any raid loot on the end reward table to bug report that immediately.