Ok not sure if anyone else has come across this issue. But there was a while there that when you saved your avatar that if you used a hair accessory that covered your ears would let you know and you had to ok it to hide your normal ears. It seems that's suddenly stopped because now regular ears can be seen through certain ears again and it's kindave strange.
Aye, those are the only ears I know that don't do the ear hiding thing, I had them for a while.
Only way I found around it was to get the ears underneath to match their colour as near as possible, or use hair that covered it lol...