Setup: 2018 Kickr, 4iiii powermeter/cadence, Apple TV 4K, Ethernet.
So my last 2 races have been successful. I have deliberately connected 4iiii to the phone on these rides, and not the Apple TV. After seeing some of the comments regarding the cadence sensor possibly being the issue. The Apple TV can only support 2 connections, but an iPhone is rated at 10 connections - although 4-5 might be the practical limit.
Anyhow, I came to think that perhaps there is a bug that thinks the cadence sensor and the 4iiii powermeter is 2 connections, which means that they both fight with the Kickr over the maximum capacity of 2 Bluetooth connections that the Apple TV can serve. If the apple remote also uses BLE for commands, then this might be the issue for me.
Anyhow. On the last 2 races I have only allowed the Kickr to connect to the Apple TV bluetooth channel, and paired the powermeter, cadence sensor AND HR-monitor to the Zwift Companion app on the phone. I have not had any issues on those rides.