Hi Juan
We realised that when the audio file hasn't been downloaded, as it's greater than the download threshold set in the app (20MB on wifi) it will start the download but also load the web player by directly opening the Moodle web page for it (same as if you opened that audio file on a desktop).
If the file is already downloaded, or is below the download threshold, it will be downloaded and opened in the proper audio player.
Juan - do you know if the download threshold has increased in later versions of the app?
Thank you
Michelle