I have added a custom ringtone to my Galaxy watch 6 moving the MP3 file to the ringtone folder on the watch with a file manager app, I can select the ringtone from either the watch or my phone and the ringtone will play, however when I receive a call the ringtone is silent. As soon as I select an inbuilt ringtone the watch will play that tone when I receive a call. How can the watch play the custom tone when I set it from the watch or my phone (proving the MP3 file actually plays) , but when I receive a call its silent ?