Cleaning the Windows (10) Recycle Bin option is always checked, but the results of a cleaning always show more than 6,000,000,000 kb have been cleaned each time I try (even after immediate, successive tries), while clicking on the Recycle Bin icons shows it empty.
It sounds as if you may have a corrupted Recycle Bin.
It happens more often than you may think, but most people wouldn't notice for a while if at all. (You probably wouldn't have if you weren't using CCleaner)
See this for how to reset and so fix a corrupted bin: