When a switch changes and then changes back in HA, it usually means that HA isn't receiving device events from Hubitat. If the switch itself isn't actually toggling, though, it could also mean that HA can't send commands to Hubitat.
When you flip a switch to "on" in HA, HA updates the switch's visible state to "on", and the integration sends an "on" command to Hubitat. Hubitat turns on the switch, then sends a state update event back to the integration in HA, which updates the internal state of the switch in HA to "on". A couple seconds after you toggled the switch, HA goes back and double checks the HA device's state; if it's "on", the UI toggle stays on. If, however, no event was received from Hubitat, the device's internal state will still be "off", and HA will flip the UI toggle back to "off".
The best way to diagnose things from the HA side is to enable debug logging for the integration, interact with a troublesome device, and see what the log shows. In your