How can I identify unmatched albums in Apple Music?

Backup your library to external media.

Ensure anything you want to try rematching is stored locally on your computer.

Create a new empty library and enable Sync Library.

Locate items of interest and delete from your cloud library.

Switch back to the original library. These items now have a cloud status of Removed.

You can right-click and use Add to Library to see if they get either correctly matched or uploaded.

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There are many ways to backup. Time Machine is a very effective set and forget until you need it service that is built into your Mac, you just need to make sure the Music folder is being included. This isn't absolutely necessary right now, but it is good practice. See Back up your Mac with Time Machine - Apple Support.

To use a different library on your Mac hold down option as you open Music, then click the choose or create options as appropriate. See Use multiple libraries in Music on Mac - Apple Support. Then see Use Sync Library with your Apple Music subscription - Apple Support to give your new library access to your cloud music library. You could also do the deletions from an iOS device or any existing secondary library, just not the primary library that has the physical tracks you want to try to rematch or upload.

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Uploading can be better than matching, at least you know you're always going to hear your version and not some mismatch.

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