I'm running into this problem with a more complex OpenStudio model, but I've replicated the problem in a simple one-zone model. As far as HVAC goes, all I've done is make an air handling unit with two fans and water coils connected to district heating and district cooling. Its temperature is managed by a scheduled setpoint manager set a constant 12 C. The zone is served by the AHU with a VAV reheat. The zone's cooling setpoint is 21 C and the zone's heating setpoint is 20 C. The model runs, but only shows results for heating; no cooling. Perhaps there is a setting somewhere preventing the building from turning on cooling?