NOTES NOT PLAYING ON IPAD

I have a song where the notes for xylophone are not being played on my ipad from high mi on.
On my computer the notes are playing, but not on my ipad.
Strange thing is that those notes do get played in another song.
(same note, same instrument, different song)

I also tried creating a new file, putting in al the notes by hand, in stead of copying from the old file, but also here the result is the same, the notes are being skipped when playing the song.

Is there a remedy for this?