can't paste files in the files app

hi all.
I have been experiencing this issue for years now, and wonder if anyone has a solution.
Whenever I try copying and pasting files in the files app, the copy action appears to work, but long pressing on the area which shows how many items brings up a paste button but it does nothing.
I'd even asked a sighted person, and she said nothing appears on the screen when that context menu opens.
Does anyone know how to do this without moving the files somewhere else?