Full storage alert, but no


Im having this super annoying alert telling me that my villagers “cant find space for storing”, and that i should build up some more.
I cant understand that because i dont even have half of my entire storing capacity full and im having this…
Plus, im also having villagers dropping items everywhere and not stocking them until that specific item is demanded (thats the only time when its carried somewhere).
Also, i have available workers not assigned to any task, so lack of labourers is not the answer to this.

Thank you.