I just moved my four Sandboxie sandboxes from C:\Sandbox to D:\Sandbox because C: drive is SS and D: drive is a disk, and I had read an article about the life of SS drives.
I have always had Sandboxie ticked so that CCleaner could clean the sandboxes (which I only use for browsing), but.I found that CCleaner did not clean the sandboxes in their new location. I fixed this fairly easily by adding the four sandboxes separately using Options --> Include, and left Sandboxie ticked.
I was surprised, however, that CCleaner didn't clean the moved sandboxes, because I thought that it would read.the new sandbox location from the Sandboxie INI file. Is this perhaps something that CCleaner may be taught to do in the future?
I believe that CC's be safe rationale is to clean only the install-default named files and folders from the system drive. It cannot determine whether any folder names on other drives are candidates for deletion or whether they have been moved there for other purposes, so it ignores them. Non-system stuff has, as you have found out, to be entered in the Include list.
Thanks, Augeas. That makes sense because safety with respect to deleting possibly important stuff trumps cleaning.
This means that the only solution would be for CCleaner to issue a warning that the sandboxes were in a non-standard position and so need indivdual attention. But if you knew enough computing to understand that message, you would already have realised that the sandboxes weren't being deleted, and you would also know how to fix it.