I encountered this issue while shopping at a village. I picked up a stack of 11 boards from the ground, which made my character unable to move due to becoming overencumbered with other items in my inventory, so I dropped all 11 boards on the same spot. After exploring the buildings for any other available goods, I noticed many villagers were bunching up near the boards as though intending to pick them up but nobody did. I picked up the boards again and dropped them indoors, which made the crowd disperse.
It seems that the villagers' AI wanted to reclaim unpaid boards that were dropped outdoors, but the total weight of the stack may have prevented the NPCs from taking them.