Put the summary of the bug you're having here

*What I expected to happen was
that a cactus block would fall to the ground so I can pick it up but it disappeared when it landed on the cactus root block instead.

What actually happened was...:
Describe what happened here

Steps to Reproduce:
1. Chop down a cactus that has more than two blocks
2. (This sometimes happens with two cactus blocks on top of each other) The cactus block that you chopped down has disappeared within the original cactus block
3. Now watch as you get no cactus and a cut cactus