Speed at pairing screen but not during race

My setup is Tacx speed and cadence sensors and Apple Watch for pulse. My bike is hooked up to an old dumb B’twin trainer.
At the pairing screen I get both speed and cadence readings but as soon as I enter a race my avatar is standing still and speed is 0.
First time after install it worked perfect but no luck after that.
Anyone got an idea how to solve this?

Are you still on the trial?

Now I feel really stupid. Case closed I guess…

No, case is no time closed.

Check out this link, you may be able to extend it a little: https://support.zwift.com/en_us/zwift-free-trial-B1WDzRJBX