It is not uncommon for the thermostat and mobile app to differ by 1 degree.
This is due to rounding. The thermostat itself rounds down as the temperature drops and rounds up as the temperature increases.
The thermostat sends the raw temperature reading data up to the cloud with a single digit after the decimal. The cloud processing rounds to the nearest whole number and does not take into account whether the temperature is increasing or decreasing.
Unfortunately, there is no practical way for the cloud to do what the thermostat does.
If you have any questions or need assistance, please contact American Standard Home Customer Support via email at firstname.lastname@example.org or call 1-877-374-0697, Monday-Friday 9 AM – 8 PM ET, and Saturday 10 AM – 5 PM ET.