Tuff blobs doesn't generate between heights 0-16

On the changelog, it's been stated that tuff blobs can be found at the heights of 0-16, But I can't find any single tuff blobs at those heights.

Reproduce

• Create a new world
• Go into spectator with night vision (easier to see this way)
• Go go between Y:0 and Y:16
• Fly around a bit
  Notice no Tuff blobs