Using the Altitude Hold feature requires the use of all sensors on your HoverflyPro. It is important that they are set-up and calibrated properly. Follow the Auto Level setup guide before proceeding any further.
1. Use the setup client to verify your Altitude Hold switch is functioning correctly. Also verify that you can change the Altitude Hold gain.
2. Start with the altitude hold gain set to a low value (25% is a good starting point).
3. Enable Altitude Hold while flying
4. Increase the gain until you see oscillations in your altitude.
5. Reduce the gain until the oscillations are gone.
This should complete the set up of the Altitude Hold feature.