In my game, I asked my mason to create 40 stone fences. I come back to find around 6 not including the one that was inside a pumpkin basket I later found out that there was several fences in each place. Also a hearthling put a food basket inside of a rotten one (in a stockpile).
Yeah, this happens even when your HL are mining. It may be a bug but fortunately not blocking you 