Why does the Twitch alert have no sound?

So,

I wanted to set my Twitch alerts to see that everything worked, except that the follower alert worked. If I add and save an mp3 file, reload the page and go to the follower alert, the mp3 file is simply gone. Do you know what I can do?

(use streamlabs.)

Nevermind. Sound is now playing I used the old version of SL.