Steps to reproduce :

1. Make a closed area 1 block tall
2. Place a trapdoor at the start and start crawling 
3. Fill the inside of the area with 3-tall snow layers
4. Start crawling into the snow 

Output :

• Players can see through the blocks under the snow layers 
• Players won't climb the snow layers

Expected output :

• Players will climb the snow layers
• Players can't see through blocks