It’s important to keep mind that Apple Music is designed for consumers first and foremost. It is not designed for DJs. Apple Music does many things that are convenient for the average consumer, but can seriously mess up a carefully curated DJ library.
Some of the things that might happen:
- Track info is “automagically” updated (genre, comments, ratings, album covers etc.)
- Tracks are replaced with a copy using a different sample rate
- Special/custom mixes are replaced with a boring / official version of the song
Despite that - Apple Music is still one of the better options for managing your DJ library, especially in Djay Pro. It is also very convenient if you need to use different DJ software or hardware platforms. Just make sure to turn off all the options that let Apple Music automatically make changes to your library.