I have no idea specifically which driver you are using, or which specific device model/firmware you have...
This driver works fine w/both a setlevel of 0 and the off command on all my GE 14294 devices. It is for zwave plus non-motion GE/Jasco/Honeywell dimmers and I assume that is the one you are using:
https://raw.githubusercontent.com/Botched1/Hubitat/master/Drivers/GE-Jasco%20Z-Wave%20Plus%20Dimmer/GE-Jasco%20Z-Wave%20Plus%20Dimmer.groovy
If so, and you followed the installation directions in the driver thread ( [RELEASE] GE/Jasco Z-Wave Plus Dimmer Driver ) and setup the preferences, then hit save preferences. Then I'm at a loss. Maybe a different firmware version (?). If that is the case, it will be kind of hard to troubleshoot on my end without a device with the same firmware though.
You could do a "hail mary" and try the dimmer driver for the new GE Enbrighten dimmers. Their firmware and capabilities are very different than the old GE 14294 dimmers... ( Hubitat/GE Enbrighten Dimmer.groovy at master · Botched1/Hubitat · GitHub ).
If it is not one of the new shallow mount Enbrighten models, though, I would definitely not expect it to work - again, unless Jasco/GE slipped really new firmware on the latest GE 14294 dimmers.
