From the patch notes:
Good luck to the certifiably insane among us who decide to do these clear quests. They'll need it.
Quitting the game after starting a quest and reloading still resets it to the "activate the rally point" stage. Starting the quest again re-generates the entire area and respawns all enemies you are supposed to clear. Just tested it.T5 clear and fetch/clear quests will have QL 6 items as a reward
Good luck to the certifiably insane among us who decide to do these clear quests. They'll need it.