Listening to Music
Due to Android's open source code nature, we can't guarantee that all external music apps interact perfectly.
To increase the chance of it syncing properly with our in-app player, it's best to create music playlists directly in the "Playlists" folder of the device .
Other than that, using another music app such as Google's Play Music is also an option.
Just start the music in that app, and continue the workout.