If you find that your rider isn't moving in game, and you've got a zPower setup (ANT+ or BLE speed sensor plus classic trainer), it's likely for one of the following reasons:
You didn't select a classic trainer after pairing your speed/cadence sensor.
After you pair your speed/cadence sensor on the pairing screen, you need to select the trainer you're using from the next menu. You can find an overview for this process here and a step-by-step walkthrough here.
Your ANT+/BLE signal is receiving interference.
Your speed/cadence sensor isn't set up properly.
If you have a magnet-based sensor, but the two aren't set up in proper alignment, you can spin without your efforts actually registering. Verify that the magnet and sensor are facing each other and close enough together that you can spin the wheel by hand and get a reading on the pairing screen.
You should also make sure that nothing changes when you put your bike under load. We've heard of cases where putting out a big effort causes the sensors to go out of alignment due to the trainer/bike frame/tire shifting its position.
You're using ANT+ sensors, but not a USB2 ANT+ dongle.
If you're trying to pair with ANT+ sensors and you ever see a "No ANT+ dongle found" message when you start Zwift, it could mean your ANT+ dongle is not the correct model. See our troubleshooting article.
The speed sensor battery is dying/dead.
Everything else seems set up correctly, but you're still not moving? Try replacing the batteries. Zwift needs to send signals several times a second, so a battery can still seem functional on other devices like a bike computer, but be at too low of a level for Zwift.
I tried all of these - no luck.
If you still can't get moving after trying those steps, it's possible your hardware may be faulty. If you have a bike computer or other software you can verify their functionality on, check your sensor there to verify it's functioning.
If they do work, it's possible that there's a compatibility issue with Zwift. In this case, submit a support ticket and we'll look into it with you.