I experienced an odd ringtone problem yesterday. I have set some MP3s I have transferred to the phone s the ringtones associated with a couple of specific people - all of them have worked successfully at least once. Yesterday I heard a tone I couldn't identify for an incoming call from one person I had assigned a custom ringtone. I was surprised, dealt with the phone call and then later looked at the settings for that contact entry. On the main contact screen under ringtone it showed "Unknown", but then when I opened up the window to select the ringtone, the list contained the Ringtone I had originally selected, and in that list it showed it s selected. However, going back to the summary screen for the contact still shoed it as unknown.
I used the file manager to confirm the mp3 file was still on the device (it was) and could play through the media player (it did). I restarted the phone, checked the contact entry again, nothing had changed - it still showed the ringtone as unknown. I was in the middle of other things, put the phone aside for about 8 hours - it was just on and used very lightly during that time. Last night when I went back to the contact details to try and figure this out, the ringtone was correctly listed and now works fine.
Seems odd.