Missing libraries in the new iOS app

[tom80H]

From the related announcement.
TL;DR: you should use Plexamp for music libraries.

@PlexInfo

Here are some feature changes that may affect you:

Personal Media features:

• Music and Photos: We have built dedicated music and photo applications that are companions to the Plex app. Plexamp and Plex Photos are where access to music and photo libraries will live moving forward. As such, music and photos access will no longer be available within the regular Plex application when it gets updated to the new experience. Both companion apps are still in active development and can expect updates soon.