I see, this is a special situation. Technically based on the established Alarm.com policy in 2018, the CT100 is no longer supported and on new Alarm.com accounts it was not controllable for a long time.
They have actually re-enabled it for use, so you will see it in your account and can use the CT100, but they still cannot fully support it and recommend different models. It was one of three thermostats that they discontinued support for in 2018.
I cannot guarantee functionality, but one thing that seems to be different between the two accounts is the firmware version of the panel. It seems both thermostats on one panel show no Auto mode selection in Alarm.com, but both on the other panel do.
You could try updating the firmware on both panels to the latest (2.5.5) and see if there is any change.