Add-on Switch will only turn light on

Red Series dimmer
Neutral setup
3-way - 2 switches, 1 light
using GE add on switches.
I’ve verified the wiring. I have load and line in separate boxes with neutral. I’ve verified configs thru the Hubitat hub and manually on the switch. The add on switch will turn the light on, but not off. It works to turn it on and to turn the dimmer brighter, but the down button doesn’t seem to work at all.
In my searching I’ve seen the opposite problem where off works but on doesn’t, but those solutions didn’t work for me.

Just to confirm, your Aux switch is installed the first (line) or second (load) box? Obviously load* is passed through the second box (e.g. BLK-BLK wire tied) with only Traveler and Neutral connected on the Aux switch.

I only had similar issues when I had parameter 22 incorrectly. I would set parameter 22 to 0, save, and set it back to 2 (momentary) again. I’ve had to do this after a firmware update even though I’ve had the parameter set for months.

Just something to try.

What firmware? There were several releases that reported Aux “optimization”. Not sure exactly what those were, but flashing a newer firmware if you’re at a lower one might help.

Beta

v1.61 Z-Wave MCU (Target 0)

v1.45 Holtek MCU (Target 1)

Production

v1.57 Z-Wave MCU (Target 0)

v1.45 Holtek MCU (Target 1)

V1.61 - 10/19/2021

Fixed - Dimmer sending duplicate reports in certain scenarios while being controlled by certain hubs.

V1.57 - 06/29/2021

Fixed - Optimization of Aux mode in neutral setting.

Fixed - The inoperative issue after changing parameter 8 from high value to low value.

V1.56 - 05/10/2021

Fixed - Further optimization of Aux switch support in neutral and non-neutral.

V1.55 - 04/28/2021

Fixed - When parameter 52 is set to 1 the physical button press would not turn the load off

Confirmed, the aux is on the load side.
I’ll try that.