Cadence maxes out at 63

Using Zwift through Apple TV with Kinetic Smart Trainer.
When connecting Garmin cadence sensor directly it works fine (but I don’t have enough connections to also include HR).
If I connect cadence through the Companion app or through the Viiiiva HR monitor it allows all devices to connect but cadence never exceeds 63 rpm even when upping actual rpm’s to 120+.