Top of grassblock in hand is gray in 19w40a snapshot

What I expected to happen was...:
The normal grass block texture to appear when holding the block in my hand.

What actually happened was...:
The sides appeared to be normal, however the top of the block was fully grey.

Steps to Reproduce:
1. Run minecraft 19w40a
2. Go into a creative world
3. Hold a grassblock in your hand