This bug is still present as of CCleaner 5.47.6716, and the entire reason I installed the program was for this feature. My search for duplicates across 3 magnetic hard drives, matching by file size and content, and ignoring files under 100MB in size shows there are duplicates, but when I select duplicates and click "Delete selected", the program takes a very long time to complete given that deleting a couple dozen files should take a couple seconds at most, and then reports some files couldn't be deleted. UAC is not an issue, AV is not an issue, I can open a command line as a limited user and delete the files that the duplicate finder fails to remove. The program is set to use normal delete and not secure delete. I did notice that "Options>Wipe Free Drives" seems to suggest that two of my magnetic hard drives are SSDs, but this is wrong.
I did see that the files that failed to be deleted are not grayed out, so at least it's easy to skim through the list and manually delete the offending files.
