I found that CCleaner doesn't any more detect files located in C:\Users\USERNAME\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup if they have the extenesions: bat, cmd, pdf, doc, txt.
First 2 file extensions are very dangerous, but also pdf or doc are so, if those files are exploiting some bugs in their assigned software's for opening.
PS: Those file extensions are the only one that i tested on CCleaner v5.19.5633 (64bit), but i think it could be more.