Playlist doesn't save order

[Palacius]

Hi! Whenever I edit my iOS playlist and change the order of its songs (by the way, it would be great to add the option to order it alphabetically), it saves the changes i make. However, for the past two weeks, if I add new songs, the app 'deletes' the changes I have made from a certain point and the songs appear on the bottom of the playlist. It's quite annoying, since I have more than 500 songs on that playlist, and it takes a while to rearrange 20-25 songs.