It could be that while your trainer and Zwift are physically paired the communication is off. I would unpair the devices by power cycling your trainer and force closing the Zwift app (swipe it away) on then your reset your Ipad. “On switch and main button held together until apple symbol comes back”.
Oh, and make sure your trainer is not grabbing another device, like an app on your phone.
This should get them back in sync but also make sure your Zwift app is up to date.