Fairly new to the game, and I have started grinding through the artifact challenges. I have hit stage for and it seems I have come to a grinding halt. I need 3* gear to move on. I have gone through the sewers about 15 times now and haven't seen any of them. Am I missing something? Quest says it should be normal should that is what I have been running it on. Or is this just that much of a grind for these artifacts? 

Thanks in advance