I have Elements 2020 with Win 10. Just recently when I open Organizer there are no pictures. Tags, etc are still listed but no pictures. there should be thousands of them. I tried restoring the Catalog--I only have one-- but there still are no pictures.
If I remember pictures also used to be at C:\USERS\......\PICTURES\ADOBE\OTHER PHOTOS but that folderr is empty now.
Could you please confirm the media count of your catalog? Also, did the backup and restore operation completed successfully?
Please note, when you backup/restore the catalog using Full Backup, media is copied in the backup & restore folders itself. It is nowhere else copied on the hard disk. Could you please check if catalog media is present in backup/restore folders?