Why does the Workout Companion app quit when starting another app on my watch?
The Apple Watch can only run 1 workout app at a time. This is because workout apps require continuous feedback from the watch's sensors for distance, heart rate, etc. The Watch cannot provide this feedback for multiple apps at once.
We've implemented a safeguard notification to make sure you're aware that the Workout Companion stopped recording once you started another workout app on the Watch.
We recommend choosing 1 workout app to run on your Watch at a time.