How come Windows says I still have files in a folder when it's empty?

I’ve been organizing files in my documents and I notice that sometimes when I empty out a folder and double check if there’s anything I left out by clicking on properties, it says that I have like 2 or 3 files still in the folder. Yet, when I move into the folder, there’s nothing there. I have Windows set so that it reveals hidden folders, and even still the properties tab says there’s data in the folder despite nothing being there. What gives?