Finder never finds anything

There is nothing in my Spotlight Privacy panel either, and what I was suggesting is that you temporarily drag your Macintosh HD drive icon into this panel, and then abruptly remove it. That triggers fresh Spotlight indexing. Of course, if you have not selected relevant Spotlight Search Results categories, they won't be indexed, and the Finder, which depends on Spotlight indexes, will not find what you seek. Just setting Finder Preferences to search for everything does not mean that Finder itself is doing the searching…

Are you using Spotlight search? I find that's less likely to find what I want than using the Finder's cmd-F (or File/Find), and in the Finder search window that opens, select Name and Matches or Begins with, then enter your search

Forget finder & Spotlight - they're both useless for what most people want in a standard search. I use an app called Find Any File - so much easier than Apples hopelessly convoluted 'solution'

As I said, Finder relies on a properly configured and indexed Spotlight database to locate anything. Give this a try in either Spotlight, or a Finder window search field:

name:foo

where foo is the case-insensitive name, or substring in that filename. Spotlight relies on your using keywords as my previous link references point out.

Set Finder Preferences > Advanced >

and give this a read, Narrow your search results on Mac, from the macOS User Guide. This presumes that you have setup Spotlight to index your hard drive with specific search result categories. More info on Spotlight.

+1 👍