LK-99 is a quasi two-dimensional material, and one which seems particularly challenging to synthesize in a bulk polycrystalline three-dimensional mass. Even the original researchers stated that they'd "get it right" only a fraction of the time, and that their famous floating cracked-disc is still impure.
I think that there's no reason to assume that negative results right now are conclusive, whereas positive results are strongly indicative.
I think that there's no reason to assume that negative results right now are conclusive, whereas positive results are strongly indicative.