Steps to reproduce
Find/grow a nice long vine
Place the gravel block against it
It will cause a suspended vine (but that is a separate already reported bug), and it will cause the gravel/sand to be suspended
If you look on the bottom side you will notice a vine holding it up, therefore the bug is that vines on the underside of a gravel/sand block will hold it up, but not one which is against a block (you can reproduce this by dropping gravel/sand a block or more above a vine which is placed against a block)
Comments 3
The description of MC-29405 is ok. Reopened that.
if a mod could check this (not a duplicate of MC-29405, i was asked to file a different report due to insufficient description