Remote capabilities are limited by the model's design and safety permissions. An app feature list does not mean every command is available on every appliance.
What the observation means
Monitoring status, changing preferences and starting heat are different actions. A missing start control may be intentional rather than a connection failure.
A useful next step
Check the official feature description and use the local controls as instructed. Do not seek hidden menus or third-party workarounds to bypass restrictions. If the advertised supported function fails, report the model, app message and normal local behaviour separately.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.