I have a newly installed Amana ASZC1803612 stage heatpump with a AVPTC313714 AHU that has 10kW of backup heat installed. This is being controlled by a CTK03 communicating thermostat with the Redlink gateway and an outdoor sensor.
This is replacing a 3.5T air conditioner and propane furnace.

The new system seems to be working just fine except when it defrosts. Fortunately the temps here have been warm enough that the outdoor coil manages to stay above 30* most of the time.

Here is the sequence: Unit is running in heating mode, usually on low stage. Defrost is initiated, AHU goes to high fan, compressor fan stops, after a minute of so, compressor fan starts, steam blows off coils, AHU goes to low speed, runs for a minute then stops, Compressor is still running. Shortly after that the thermostat shows an error: "No Indoor Air Flow". The Heatpump Diagnostic menu shows the following error: b0: No ID airflow

This has occurred twice, both times after a defrost cycle.

Any ideas what is going on here?

One other issue, probably not related. If I linger on the Comfortnet User Menu> Diagnostic screen for more than a minute, the thermostat display locks up, and then the thermostat reboots.

I will be getting the installer back on Monday to look at it but would like some background from the collective wisdom of the Pros.