Thanks for verifying the firmware version, guys.
Our QA team checked a Tacx Flux and Tacx Flux 2 on both AppleTV OS and iOS, which covers all three of you reporting in. We were able to complete the spindown test under all combinations of these things.
They gave some info on how this spindown works: once you exceed the speed threshold, the trainer sends commands to the Zwift app via Bluetooth FTMS: a stop command, a success command, etc. These commands are sent only once. If there’s local interference disrupting your Bluetooth environment, it’s possible these commands were not received by the app, and the test gets stuck. This is what we think might be happening for you three.
I took the liberty of looking at the partial log files uploaded to the server for each of you from your latest sessions, and each of your log files are showing different BLE qualities
You can verify by uploading your log.txt file to zwiftalizer.com. Here’s how to locate your log files for iOS. AppleTV log files are locked down.
Here are some ways to improve Bluetooth and ANT+ inteference. We hope this helps the in-app spindown test results.