ambience ringtones not persistent

How to reproduce: - Load some music onto my SD card (fat) - set standard ringtone to a mp3/ogg from the sd card (i don't think this is necessary) - create a custom ambience - change ringtone for this ambience to a mp3/ogg/flac from the sd card (works fine) - reboot Actual behavior: - ringtone is reset to the standard ringtone also found on the sd card (if gallery is quickly opened, the ringtone for these ambiences shows for a few seconds) Expected behavior: - the custom ringtones should persist ... Maybe there is a workaround if the Music files are put onto the phone itself. I haven't tried it though.