Today I was unable to pair both the trainer and the power meter with the Zwift Apple TV app at the same time. Either device can be paired without the other, but not both together.
If I pair the Elite Qubo Digital Smart B+ trainer as the controllable trainer first, it gets selected as the controllable trainer and also power meter. When I unpair the power meter, it gets stuck in the loop I showed in the video above. If I choose the Stages power meter as power meter first before controllable trainer, the Qubo trainer will never appear on the BT pairing menu.
The Apple TV SW version is 1.0.44368 - published 31.12.2020. This information is taken from Apple TV app information. I hope this is not the version that will stay for the entire year as the date suggests.