Hiding an SSID would require a reboot, so the AP could stop broadcasting that SSID and remove any users who would have previously seen it. Adding an assignment rule to a user profile could potentially change how all connected users are classified, so that is again something I would expect to take a complete configuration to update. Editing an assignment description doesn't sound like it should require a reboot, but I'd need to see specifically what you're updating to be sure.
The main causes of delta updates failing are either that the configuration change requires a reboot, or that the firewall port is not open correctly.