All sensors connected, but avatar won't move

Hello!! I am running a Elite Power Mag classic trainer with new Garmin Speed 2 Cadence and Speed Sensors. Zwift sees my sensors, and I’ve connected my turbo trainer, but when I get to the ride, I can’t move. I only have the option to run Zwift on my Iphone 7plus and have been doing so happily until one day last week when it stopped seeing my sensors. I had an old Coospo speed and cadence - so thought the problem was that (it was pretty ancient so bought new Garmins). Still nothing working. I’ve been through everything on the article “Not Moving In Game” - its not the batteries (all replaced), and I’ve selected my turbo trainer. I’ve deleted and re-downloaded Zwift. I’ve checked the sensors are not being picked up by the bluetooth on my phone before Zwift gets a chance - that’s not happening either and appears as it should be. Any ideas greatly appreciated!!!