Open Radar

 
Summary:
I was playing an album (adding the tracks to Up Next) after turning iCloud Music Library back on. 6 tracks had played, and then when starting the seventh, iTunes hung for a long time, before eventually coming back.

Steps to Reproduce:
(roughly:)
1. Turn off iCloud Music Library
2. Add 2 albums to iTunes
3. Add first album to Up next
4. Play first song by double-clicking in Up Next
5. Turn iCloud Music Library back on
6. As last song of first album is finishing, add songs from second album to Up Next
7. At some point, iTunes says it failed to update Genius results
8. Click Store > Update Genius
9. From the spinning iCloud icon’s popover (top right corner of main window) click the reload circle next to the failed Update Genius item, causing it to disappear
10. The sixth song from the second album finishes playing

Expected Results:
The seventh song begins to play

Actual Results:
iTunes hangs for several minutes, with the Apple logo in the status display at the top of the screen, with no song playing and the spinning iCloud progress circle frozen. The cursor is beachballing. Eventually, after taking a sysdiagnose, the next song does start playing. I would have force-quit iTunes if I weren’t in the middle of writing this bug report.

Notes:
I’m running OX X 10.10.5 on a 17” retina iMac