m4r can't transfer to iPhone 11
I customise a song to ringtone file (m4r), I tried to use iTunes to import it to my iPhone 11, but the ringtone doesn't appear in iTunes. I tried Drag and Drop to iPhone, got an error message (iPhone can't play the file....). I used manual copy and paste to iTunes & iPhone, nothing works.
Could someone help please, Thank you
iPhone 11, iOS 13