Vines cannot be placed below non-solid blocks

Unable to reproduce. Are you sure the vine is a "source" vine block? The game could be registering it as a vine hanging off with no attached block, and as such being destroyed by anything destroying the vine above it. That might be a bug entirely of its own, however.

I can confirm. Vines below fence/cobble wall are disappearing in 1.12 pre 7. Also you can't place vines below fences.

Of course its a source vine, i put it there

@@unknown I made the report a little bit more generic, I hope you are fine with that.

Confirmed for release 1.12. Issue first occurs in snapshot 1.12-pre1 and affects every version after that.

The issue affects any transparent or non-full block placed above vines, such as glass, stairs, torches, ladders, string, chests, etc. Interestingly, it does NOT affect top half slabs or upside-down stairs.

Vines normally attempt to "connect" with the underside of full solid blocks above them (changing the block state "up" to True). If that's not a full block, rather than remaining "unconnected" (block state "up" set to False), the vines are instead deleted and cannot be placed.

The vines CAN be placed below fences, etc. using the /setblock command, but they are immediately deleted when they receive a block update.

In version 1.12, these are the blocks I have found that now impact vine growth below them. In the Image from left to right:

• Glass, including stained glass

• Slabs, bottom only

• Stairs, bottom only

• Cobweb

• Torch

• Chest

• Ladder

• Fence, all

• Iron Bars

• Glass Pane, include stained glass pane

• Enchanting Table

• End Portal Frame

• Ender Chest

• Cobblestone Wall, including mossy

• Tripwire (above anvil in image)

• Anvil

• End Rod

• Shulker Box

• Sign

• Bed

• Skull

• Banner

• Lever

• Restone Torch

• Button, including wood button

• Trapdoor, top and bottom

• Fence Gate

• Tripwire Hook

• Trapped Chest

• Daylight Detector

• Hopper

• Iron Trapdoor, bottom only

• Beacon

• Cauldron

• Brewing Stand

EDIT - Not in image:

• Grass Path

• Farmland

Still in MC 1.12.1 vanilla

Same in 1.12.2

17w45b affected