Unfortunately a lot of Baloo issues are solved like that - I sometimes find that I used incorrect tags on some files, and if I remove the offending tags from the files, Baloo still finds the old tag, even if I remove that tag from all the files so it shouldn’t even exist. And the only way to solve this is to clear the database and reindex everything.
There’s a terminal command to do it in one go:
balooctl purge
If you use it, note that balooctl will start to immediately output it’s indexing log to the terminal, so you’d want to close the terminal after you run the command - it will not stop the indexing, so there’s no need to worry about that.
baloosearch -d ~/your-folder "what you are looking for"
It seems that basing your search on a particular folder has been problematic, You’d see this behaviour in Dolphin if you go to “your-folder” and search from there…