Restart Tracker. We recommend to use the "-v 3" option to log with maximum verbosity to know what is happening. The log is printed on the console, but also in two files:

Check these files. You may find messages like "Unrecognized option 'X.Y'" and that can give you clues of what is happening, specifically if something goes wrong (it should never happen if you follow this tutorial).

You can check that tracker has read the .service and .metadata files correctly using the tracker-services utility. With -s flat, it asks to the daemon all available categories. With -p it does the same with properties. Check that your new categories are in that list.

You should be able to use tracker-files with -s [MyCategory] to check what files have been included in your new category.

You can try to search with tracker-search for some words you know are there (i.e. filename or words in the extracted properties).