search function not working on external drive

get your Mac showing the correct search results when using Spotlight to search.

Try the steps here to index your disk:

"macOS Ventura or later

1. Choose Apple menu  > System Settings.
2. Click Siri & Spotlight in the sidebar, then scroll down and click Spotlight Privacy on the right.
3. Drag the disk or folder that you want to index again to the list of locations that Spotlight is prevented from searching. Or click the add button (+) and select the disk or folder to add.*
4. From the same list of locations, select the disk or folder that you just added. Then click the remove button (–) to remove it from the list.
5. Click Done, then quit System Settings. Spotlight will reindex the contents of the disk or folder. This can take some time, depending on the amount of information being indexed."
6. THIS NEXT STEP IS IMPORTANT and missing from the Apple Support instructions!! Press Cmd and space bar, which opens a Spotlight search. Start typing anything (e.g. your name), but DO NOT HIT ENTER!! You will then see an Indexing status bar. Leave the Spotlight window open until the indexing is finished (15-30min).
7. Once the indexing status bar has finished, go back to Finder and the search should work. It's kind of amazing as is searches inside the documents for the same word. If you are searching for a saved Staples receipt, it will find that receipt as well as other files with the word "stapes" somewhere inside the file. Very cool!