Windows Photo album SQL database issues

Question

i spent numerous hours sorting some vacation pictures (stored locally) in order to create an album with Windows Pictures (windows 10).

Everything was going fine until all pictures from one of the folders I used disappeared from the album (but still exist in the source folder/ the "collection" section of the Pictures App).

I found that the link between the pictures and the album is made through an SQL database located here username\AppData\Local\Packages\Microsoft.Windows.Photos_8wekyb3d8bbwe\LocalState

Any idea on what happened to avoid having to sort those pictures again? How could i find previous versions of the database? (the one listed in the properties section of the file is too old...)

thanks for your help!