Its possible in my case it was not dry enough to begin with. Sealed containers keep the moisture IN as well....
I left the most recent batch of starch powder in the dehydrator a whole extra day and it made nice hard granules that still pour like sand. I don't know how I messed up the manganese powder but it at least does still pour correctly. I do have silica gel packs inbound, I'll see what I can do with those.