The key change: Move the Database.bookAuthorModel.create() block outside the if (!author) check,

so it runs whether the author was just created OR already existed in the database.

This bug was visible when using "Match Books" for a library and the outcome was books had no author(s) assigned
despite the custom providers correctly providing those values.

server/scanner/Scanner.js

@@ -259,7 +259,7 @@ class Scanner {
             SocketAuthority.emitter('author_added', author.toOldJSON())
             // Update filter data
             Database.addAuthorToFilterData(libraryItem.libraryId, author.name, author.id)
-
+          }
             await Database.bookAuthorModel
               .create({
                 authorId: author.id,
@@ -270,7 +270,6 @@ class Scanner {
                 libraryItem.media.authors.push(author)
                 hasAuthorUpdates = true
               })
-          }
         }
         const authorsRemoved = libraryItem.media.authors.filter((a) => !matchData.author.find((ma) => ma.toLowerCase() === a.name.toLowerCase()))
         if (authorsRemoved.length) {