I wonder how you measure humidity levels of the coffee. Illy I know is quite obsessive on this point; a batch measurement may read, say, 11% but doesn’t tell you much about the spread of individual beans. I have a PPT they showed in Colombia, insisting that they prefer a narrow range of individual bean RH% but that poor drying will lead to a broad range. They prefer the Guardiola method of mechanical drying for instance.

I wonder too if storage in ziplocks might help even out the range, as drier beans absorb humidity from moister ones.