I can not put a “playlist” I’ve put together on iMac on my phone. Out of 12 songs it will only transfer the first 3
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it may be caused by lack of permission of the song. In other words, if the song was purchased under a different ID than the one your phone is logged into, those songs would not transfer. The problem could also be caused by the music file type. Say if they were .wav files as opposed to .mp3 for instance. There are other reasons as well. These are just the first two that come to mind.