I think I'm missing something really basic, but I can't figure out how to get my Runn treadmill sensor to pair with my Garmin watch so I can receive the treadmill paces on my watch.

The Runn device is working - if I pair it via bluetooth on my phone with the Wahoo app, it's found (it's named "Runn"), and does read the exact same pace I set my treadmill to. But even there, if I open an actual workout, there's no pace displayed in the workout pace (0:00) - it only shows the pace on the main screen when it shows which devices are connected to the wahoo app.

On my Garmin watch, I tried the normal "find all nearby sensors" after depairing the Runn from the Wahoo app, but the Runn never shows up. (All my other myriad sensors pair fine, and there a lot of them!)

I'm sure I'm missing something really basic here, if someone could point me in the right direction, would be appreciated!