I believe this is a firmware bug that will be fixed at some point. If the relay is disabled and power is lost, the switch defaults to off when power is restored.
When the relay is disabled via config x8, you can still control the switch through zwave. Until the firmware update is released, you may be able to do one of the following:
- Bypass the load and wire the bulb to be permanently on. I have read other posts that suggests this works, but I havent tested it myself.
- Set up some sort of timed automation that sends the ON command to the switch every 10 minutes or so. This would ensure the switch eventually gets turned back on after a power outage. Sending the ON command to a switch that is already on doesnt seem to cause any issues, but if you send the commands too frequently, you may saturate the zwave network
- Set up some sort of automation that detects if your smart bulb becomes unavailable and then sends an ON command to the switch. This has a less chance of causing zwave bandwidth issues, but is probably not as reliable as option 2.