Bug or bad luck?

@Infinite is correct. A year ago there were just as many complaints about AM’s, chest loot, as there are now. It’s all RNG.
I was riding a nice wave of AM drops, Mystic Vision giving me Scopes, fine gloves, sturdy shields. Chests with Rings or Tonics…now I’m getting rocks and feathers, but the 1-3 gems are great…?
It comes and goes, just make sure you complete all levels of challenge events as they come. The loot improvements are encouraging.