In the latest version (5.1.0.1 for 1.7.10), the items Whistle, Tombstone and Villager Editor have missing textures, so their displayed texture are the common magenta-black checkered squares.

This issue was reported on the Minecraft Forum by EnderYuuko. For further questions, please reply to this post.

(#436) known, (#477) known, (#409) and known.

A commit (13b3cca) has been applied for this, yet it worked for a older version (last time I think 5.0.7).

All I can say is that this is a regression. My suspicion looks towards RadixCore, which in MCA 5.1, requires a newer version.

Fiddlesticks.