Nether sprouts no longer generate when bone mealing warped nylium

Summary:
Nether sprouts no longer generate when bone mealing warped nylium.

Steps to Reproduce:

1. Create a large platform out of warped nylium
2. Bone meal the nylium many times

Observed Results:
Nether sprouts do not generate.

Expected Results:
Nether sprouts should generate.