I had to look up what a Lemond Wattbox is, and found this 2014 article. That’s the year that Zwift was born - so I’m skeptical that the hardware is compatible with our software.
The article notes that this is an ANT+ device, so are you using an ANT+ dongle on your computer? That’s the first requirement.
Even if the power data is picked up, this does not appear to be a controllable trainer, so don’t expect the game to change its resistance.
The WattBox is nothing more than an overpriced speed sensor that does the speed/power conversion and as I understand, it broadcasts ANT+ Power, so it’ll be compatible with Zwift.
If it doesn’t work, throw it away and install a speed sensor as shown in my video. Zwift (and most other platforms) will do the speed/power calculation for you. If you go this route, install an ANT+/BLE speed sensor to ensure better compatibility without the need to mess about with an ‘ANT Stick’.
I’m interested in this, as I am on the verge of getting rid of my LeMond trainer. I have been using the trainer successfully with Zwift since 2017, but as of July 2021 have had nothing but problems, despite many chat sessions with support and attempting multiple suggested fixes. My Garmin does pick up the power meter, but I haven’t been able to pair with Zwift using my computer. Anyone else out there with a LeMond trainer having problems?