Estou tentando implementar o backup automático do Android (Android 6.0), mas ele não funciona.

Eu recebo o mesmo erro com

10-28 22:58:06.980 600-5578/? I/PFTBT: Initiating full-data transport backup of com.myapp.package
10-28 22:58:06.981 7891-14015/? I/GmsBackupTransport: Attempt to do full backup on com.myapp.package
10-28 22:58:06.982 600-5578/? I/PFTBT: Transport rejected backup of com.myapp.package, skipping
10-28 22:58:06.982 600-5578/? I/PFTBT: Full backup completed.
10-28 22:58:06.982 600-610/? D/BackupManagerService: Done with full transport backup.

Eu tentei ativar

adb shell setprop log.tag.BackupXmlParserLogging VERBOSE

e

adb shell setprop log.tag.GmsBackupTransport VERBOSE

mas não vejo mais informações no logcat. Depois de ativar e desativar o backup, recebo esse erro. Como resolver isso?

10-28 23:53:08.699  1633  1644 I GmsBackupTransport: Attempt to do full backup on com.myapp.package
10-28 23:53:08.699  1633  1644 V GmsBackupTransport: Rejecting full data backup. user has not seen up to date legal text
10-28 23:53:08.699   599  8353 I PFTBT   : Transport rejected backup of com.myapp.package, skipping
10-28 23:53:08.699   599  8353 I PFTBT   : Full backup completed.
10-28 23:53:08.699   599  6518 D BackupManagerService: Done with full transport backup.

Eu segui o guia aquiBackup automático. Alguma ideia?