Many thermostats now use the newer capabilities when paired with ST or connected via WiFi/C2C integrations. SmartApps need to be updated otherwise it won’t detect these new integrations. You’ll need SmartApps specifically designed to work with these newer capability thermostat integrations. Here are a few examples:
[RELEASE] 5-2 Day Programmable Thermostat Scheduler (Weekday, Weekend) with Remote Temperature Sensor for each Schedule
[RELEASE] Mode Based Thermostat - Control Multiple Thermostats Temperature / Remote Temperature Sensors when Changing Modes
[RELEASE] Motion Sensor Thermostat with Remote temperature sensors, Presence detection and Schedules