Music on MacBook isn’t synching to iPhone

See Identify cloud status icons in your music library on your Mac or PC - Apple Support. When using iCloud Music to sync your collection make sure that all tracks are marked as purchased, matched, or uploaded.

If you're syncing local content over USB make sure all items are downloaded to local storage, checked/ticked, and are in the selection of content you've chosen for syncing.

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What says waiting? If your device is currently syncing be patient, or interrupt the sync if you need to go somewhere with your device and try again later. Do you have a subscription to either Apple Music or iTunes Match? If you do, and you have tracks whose status is Waiting then reboot your computer and use File > Library > Update Cloud Library to try to get those tracks to upload.

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