This is an expected answer from Sonoff.
If this cheap (probably for a reason...) device does not work satisfactorily in your environment, you can look at this one :
This device seems to be using the standard ZCL clusters and is another candidate for a Hubitat built-in (not custom) driver. You can call the guys in Santa Monica and ask them if they are willing to cooperate with Hubitat, sending a sample device to HE devs.
