Smart Lock Guest Access not working to add guest codes

Did you check to see if you have multiple locations and if so, is the app and lock installed in the same location?
You may also want to check out LUM to create/manage users if you have access to RBoy Apps: [RELEASE] Lock User Management - Door lock code manager (create, delete and schedule codes) with automatic lock/unlock, custom user actions and SHM/ADT integration (LUM)