recents folder empty Catalina

Actually putting * in the search was not showing all my files. For example I had two .txt files with the same name but in different folders: Searching for "*" only one was found, the less recent which was why I noticed. Searching for "txt" both were found.

I did a Relaunch of Finder (Opt+Cmd+Esc) and now Recents seems to be working normally. Fingers crossed.

They may not have the metadata attached if you restored from a backup.

Spotlight can get "stuck" on indexing some files. I don't have any experience hunting that down, though.

It used to be somewhat easy to go into console and find errors that would indicate where the problem exists, but the rewrite of console and the logging system makes everything difficult.

Spotlight was working for me, and Recents was not. Does that describe your situation?

Before, when I clicked on Show Search Criteria, there was nothing. That's why putting in something like "*" or "txt" was helpful for me. After I did the Relaunch of Finder, when I clicked on Show Search Criteria, there was:

Raw Query (kMDItemLastUsedDate = "*") &&

This is the metadata rather cryptically referred to above by Barney-15E. So if the Search Criteria is empty, Recents shows nothing. It's a search not a filter.

But your problem may be entirely different from mine. Nobody knows but you, because you haven't given any details of your issue beyond "empty" and "nothing helps".

How to rebuild the Spotlight index on your Mac - Apple Support

Then either a spotlight cannot index the drive or you have no files with the kMDItemLastUsedDate metadata set.

This just happened to me today. I notice it says "Search for:" above the list. I don't know how to turn the search off, but by typing * in the box I got all my recents to show up.