Leaf blocks that are transparent lose their transparency when they are surrounded by other blocks. If those blocks are half slabs, then you can see the leaf blocks change into non-fancy graphics.
The leaf texture is presumably culled to cut down on rendering, but when the block is still visible (ie next to a half block) it looks wrong.
Steps to Reproduce:
- Place a leaf block on the ground
- Surround all four sides with slabs
- Place another leaf block or slab on top of the first leaf block
- Watch the texture of the leaf change from transparent to opaque
This issue also occurs on the latest beta version 220.127.116.11 on Samsung TabPro SM-T520 on Android 4.4.2