Use the Add Control button on the Customers page to attempt adding a thermostat that doesn't appear in the Portal.
One of three outcomes will occur:
Connected to Database + Homeowner Account → Thermostat is added to the Connected Customers list.
Connected to Database + No Homeowner Account → Thermostat is added to the Queued Controls list.
Not Connected to Database → Thermostat is added to the Queued Controls list.
Items 2 and 3 cannot be differentiated by disposition in Connected Portal. The thermostat User Interface will indicate if the thermostat is connected to the database or not.