Breaking the budding amethyst as a support block doesn't break the entire amethyst clusters

Summary
When you've fully grown an amethyst on both 6 sides of the budding amethyst, and you break the budding amethyst as a support block, the bottom part of the amethyst doesn't break, instead, it stays as it floats upside down.

Step to Reproduce
1. Place down a budding amethyst, with one block gap below it.
2. Set the random tick speed up to speed up the growth
3. Turn the tick speed off
4. Break the budding amethyst as the support block.
---> The amethyst doesn't break entirely, the bottom part is still intact.