When I was trying to verify your results (posted earlier in this thread), I noticed some things. I just re-tested and here is what I found.
I started with an empty filtered Recent Folders List. Then I entered [b]C:[/b], which did not appear on this list at that time. So I entered C:\Windows, then [b]C:[/b] appeared on the list, but C:\Windows did not. So I hit the Back button, then C:\Windows appeared on the list.
Using a separate process (Cmd.exe) I create C:\testdir\testsubdir.
I entered C:\testdir, it does not appear on the list. I list the root of a different drive, C:\testdir appears on the list.
You must traverse a folder for it to appear on the Recent Folders List--that is enter it an leave it. Also, if you log off of Windows, or reboot, Recent Folders entries are all completely blown away, as they are no longer recent. Nudel is also correct in that entering a folder then closing the lister, will not add a folder to the list.
I might be wrong on this, but it also appears to me there may also be a time limit or a number limit on the number of folders Opus displays on the Recent Folders List. I seem to remember coming back hours later, looking at the filtered C:\ drive list, and noticing it empty again. I also navigate hundreds of folders a day (sometimes in an hour) and I almost never browse my C:\ drive (my work files are redirected to another physical drive). Thus it seems logical in my circumstances for folders to be quickly dropped from the Recent Folders List. Remember, that a Filtered Recent Folder List, is merely a subset of a larger Recent Folders List.
I think what John has been trying to bring up is that perhaps you would be better served by a filtered Smart Favorites list.