Setting Duplicate Finder on F:\Music\*.* in which there are many many, likely some dupes, it returns instantaneously with nothing found. This can't be right. What is to be done>
If it's returning immediately that indicates that there is something in your search settings not quite right.
It could be either the 'Match by' or 'Ignore' settings.
As examples:
If you have it set to 'Match by' name it will only find duplicates with the same name. (So duplicates with different names won't be found).
If you then add 'Modified date' then it will only find duplicates that have the same name <u>and</u> date.
Conversely if you tell it to 'Ignore' file sizes over say 1 MB then it will not look at anything larger than that.
If you could screenshot the Duplicate Finder page and post it here so we could see them then we could advise better which setting(s) could be causing the issue.