Hi,
I have been a happy Zwift runner since Christmas, on some Woodway 4Front treadmills I have at work.
However, the last couple of weeks I have had problems connecting to the treadmills. It does seemingly connect, but the treadmill speed is not translated into movement in the Zwift app.
I have the same problem with both my IPhone and IPad. We have 6 treadmills, one of which being a little older than the rest. The strange thing is that I am able to connect to the older model, so the problem is apparently only relevant to the newer models.