From Ventura (if not earlier) to Tahoe, Spotlight appears unable to index text files that start with two specific letters. Although those are exceedingly rare, this could still catch you out.
Spotlight
Notes on how search depends on index structure, effects of language on different types of search term, and the benefits and limitations of search methods.
Running the basic test on a folder in your Home folder, extending that to documents that use a custom mdimporter, to other volumes and locations, and other search terms.
This can now test and search any regular volume that’s connected to your Mac and mounted in /Volumes, using either NSMetadataQuery in the API, or mdfind instead.
New app tests Spotlight indexing and search of local files across 15 test files and two search methods. This should provide valuable clues for diagnosis.
How to find images containing objects recognised by Visual Look Up, and text by Live Text, using Spotlight, mdfind and in an app.
macOS gained Live Text and Visual Look Up when Apple declared its intent to check our images. Both are used in Spotlight’s indexes, but their function seems unreliable and highly variable.
Looks at how Spotlight adds a batch of new files to its volume indexes, and how it handles and answers queries.
A meta-search for Apple’s patents on search, and turning the incessant log chatter of RunningBoard to our advantage in following uninstrumented apps.
Supported by some of the many patents awarded to Apple’s engineers, a year-by-year account of the development of Spotlight from 1994 to 2019.
The Eclectic Light Company 