Hello there,
We have confirmed this bug and are investigating.
For all affected users, this may be an issue caused by multiple connections, as @Otto_Destruct called out. A common workaround for this is to disable bluetooth on any devices unnecessary for your Zwift activity and force close all apps that have connected to the treadmill.
Additionally, I’d like to recommend (safely) powering down and unplugging your treadmill to allow it to forget previous connections. Then, while on the Zwift pairing screen, (safely) plug in and power on your treadmill.
I will update with any further tips and news from the developers. Please continue to post or reach out if the provided workaround helps or not.