I also observerd this strange behaviour.
I ran ccleaner from r-click of my recycle bin and after ccleaner was done the recycle bin still not showed the "empty" icon.
So I ran ccleaner again but no change.
Then I r-clicked and selected "empty recycle bin" and windows asked me if I wanted to delete 2 files.
I approved and the files were gone.
I am running v3.21.1767 on w7 64 Lenovo Thinkpad.
Update: I just installed v3.22.1800(64-bit) and the problem is still there