When browsing the music library, artists, albums, songs, genres and years that have mixers available display an underlined "m", and the mixers can be invoked by pressing play.hold.

This is not the case when browsing the currently playing playlist.  I think it should be consistent.

When browsing the songs in the current playlist, there is no mixer symbol.  I think this hasn't been implemented, because the Save Playlist plugin uses play.hold as a shortcut to get into the plugin.  This is inconsistent use of the button.

If I right-arrow into a song, there is an option to create a MusicIP mix. This doesn't bring up the MusicIP mixer options in the same way as pressing play.hold from browsing a song (doesn't obey the setting "MusicIP Player Settings for Each Mix" if it is enabled).

If I right-arrow into a song from Now Playing, the artist, album, genre and year
items do not have mixers, whereas they do when browsing the same song from the Browse Library modes.

I suggest that play.hold is used consistently throughout the PlayerUI to bring up the mixers in the same way.

I suggest that the Save Playlist plugin should not automatically use play.hold.  Save playlist is available from the extras menu, and a user could customise a .map file if a shortcut is really necessary (or use a different key, such as Now Playing.hold).