No, I dont think there is anything wrong with the device, but is more like how it works. The Standby ASA Module should have the primary ASA IP as gateway in order to go and do the auto update. Remember that the standby ASA cannot pass traffic across it. So if you put the default gateway on the standby SSM module as the default gateway, it is not going to work.
Now, the other point (and I think this is the issue) would be routing, if you connect to the standby ssm module via CLI, can you ping the something on the internet? You need to make sure that the AIP have a path to reach the cloud.
Mike.
Mike