materialData for 'Moster egg' not working for GUI menu

[Squirzy]

Using the latest dev build: Build #15 (26/06/2017 10:45:42 AM) (https://ci.techcable.net/job/SonarPet/15/) on Spigot 1.12

All eggs in the GUI menu are the same: https://gyazo.com/6ddd36a0297e1f8971e4c5fc9364a36d

Using default config: https://pastebin.com/PPf1hrp2