Best I can tell, the F85 started supporting Zwift with the 2019+ model year. I’m suppressing commentary on Sole not changing the model but changing the model capability year after year. But what’s new this round is the Sole+ App which allows you to control the F85, etc. and that you can also pair certain Garmin watches, in my case, Forerunner 965 so that the F85 gets HR data from the watch displayable on the console.
But for my Win11 setup, Zwift would not show any available BT devices. Sole support not able to help. At some point in troubleshooting, I turned off BT on my phone. Suddenly I could pair Zwift with the TM and do a run. And then it made sense: The available devices could not pair with Zwift because they only supported one connection and they were paired with something else.
So now my process has to be that I make sure I’m not running the Sole+ app (which connects to the F85) to make it available to Zwift. And I disconnect my phone from my 965 (then not available to Garmin Connect or “smart” notifications), but then it’s available to the F85.
While I also tested using Zwift paired directly to the 965, speed/distance accuracy then depends a calibration method that comes down to cadence x average stride length. And this has never worked for me. But the point is that Zwift must pair with the 965 in a Virtual Run activity. But when paired with the F85, I use a Treadmill Run activity.
I hope this saves other people some time.