Anvils don't recognize color tags on titles.

Very easy to reproduce. If you have an item with a colored name, then it looses that upon being repaired. The lore stays colored, but color tags are not recognized by the anvils... presumably because the coloring symbol isn't recognized by anvil. If you want a large host of color title items for easy testing, Herobrine's Mansion should provide a fair amount. Bolded items also become un-bolded.