For some reason only about 6 of 22 players have both their UUID and username recorded in the .db file. Everyone else is "null" so they can't be added as users to other people's locked blocks. I opened the .db file and added in the missing usernames but now it's saying:
03.12 18:47:19 [Server] INFO [StickyLocks] org.sqlite.SQLiteException: [SQLITE_READONLY_DBMOVED] The database file has been moved since it was opened (attempt to write a readonly database)