Custom ringtones blocked by iOS 4.3.5 ?

I have only just got round to upgrading to iOS 4.3.5 and once I had done so my personalised ring tones had gone. If I look at the iPhone using iTunes, the ringtone files are still there, its just they are no longer in the list of available ringtones on the iPhone. All I have now is the Crapple set. I'm assuming this was deliberate and Apple don't like the thought of you having your own ringtone when they can sell you one of theirs but on the off-chance I thought I'd ask.