Sorry, no answer from me, but I'm having the same issue. I try deleting files either by right click on the file > delete; also by highlighting the file and pulling down the ellipse icon above > delete; and finally by highlighting the file, scrolling to the right and clicking the ellipse there > delete.
None of those options work. Instead of deleting the file, it creates a copy. Now I have multiple copies I want to delete, but when I try again, I just end up with another copy. And the chatbox is entirely worthless. If I can't resolve this, I'll delete dropbox, because I am so done with this.