With MC for Mac, when you upgrade Major versions, (like 21 to 22), you have to manually copy the MC database. The procedure is really easy and fast once you know it:
1. In MC21, backup your library (database): File > Library > backup library . Make note of the filename and location.
2. Close MC21. Open MC22. Restore the library (database): File > Library > Restore Library > (choose the backup file made above).
Now you should see all media in MC22 that you had in MC21.
Good luck.
Brian.