Facebook Messenger Secure Storage Download Help

Does anyone know how far back the download for the secure storage goes? I've downloaded the secure storage file but it's saying that conversations that I KNOW I've had are not there and also has files for end to end encrypted chats that I don't ever recall opening. How far back does it go? There's a chance it could just not go as far back as the conversations regarding the ones I know I've had... Any help would be appreciated!