Zone temperatures not matching setpoints during the night

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Most likely your system (fan schedule) is off so it cannot provide air to meet the load. Do you have system flow at these hours? Look at your fan schedule and also check your inputs for night cycle control. Night cycle control can allow the fan to cycle on when there is a thermostat call from the zones served, even if the fan schedule value is OFF (zero).

If Molly's suggestion isn't the reason in this case, take a look at your "setback" temperature, and the timing of related HVAC schedules which have a value of 0.5 (which would trigger operation to the setback temp not setpoint temp). The reason I suggest that is that you suggest the temp is fairly constant at 25C outside normal setpoint times. If neither works then I suggest you submit a ticket to the Support Desk with the model and they should be able to resolve it.