So even if you click it on physically it is doing the same thing?
Please post the info from the device page > Device Info > Device Data section
Looking for the Type, ID and Manufacturer mainly.
Also what driver are you using? (From the main device list it is in the Type column, and a custom driver will say "user" by it)
If its a new-ish device, it may work with my universal dimmer driver which will scan the device for all its settings. There might be a setting causing it to default to 4% which you could change with this driver: [DRIVER] Universal Z-Wave Drivers (Switch/Dimmer)