Cannot create playlists in U1 music web interface

When interactively working with the Ubuntu One Music interface (after signing up for streaming service), clicking "add to playlist" reacts as though it is working, but after doing this for several (40-50) songs, clicking on the name of the playlist results in the message "There are no songs in this playlist". Experimentation shows that even with newly-created playlists the behavior is the same.

Creating playlists on the Android app synchronizes back to the web interface with the *name* of the playlist, but while the playlist works fine in the Android app, the playlist still shows as empty on the Ubuntu One Music web interface.

Not sure if OS matters since we're talking about the web UI, but this is on Ubuntu 12.04.

Additional information: Bug verified as behaving the same when tested from multiple machines using either Chrome or Firefox on Ubuntu and Windows.