Gravel disappears when falling on plants

Put the summary of the bug you're having here

What I expected to happen was...: gravel had to drop out when it drops on plants, mid-blocks, etc.
Describe what you thought should happen here

What actually happened was...: Gravel has not dropped, and disappeared
Describe what happened here

Steps to Reproduce:
1. Put gravel / sand so that it began to fall
2. He fell to the mushrom
3. Gravel disappeared