So i was in a delve grabbing a sky shard and i noticed that the heavy sacks were re spawning really quickly... So i decided to go around the delve a few times... So i recorded it.... Apparently in Delves that don't usually have a lot of people... and have about 3 heavy stacks, find a delve like that... and you have unlimited heavy stack farming.... I don't know if this is game breaking but id assume so.. ZOS you should probably fix this before people start exploiting it...
Click Here for a video of the bug