Dragon Egg renamed into #### no matter what the name is.

So basically whenever I rename a dragon egg, even if its something like "Dragon eg" it turns into ####. I tried renaming the #### dragon egg back into Dragon Egg and it just came out of the anvil as ##########. Also, renaming like ANYTHING in the anvil to a family friendly, non inappropriate name changes them into #####.  I don't understand. Below I submitted pictures of the dragon egg, and a bow that wasn't renamable without ####.