When a painting placed on the north or east face of a wall is broken, its corresponding item entity is spawned within the wall. Because it is in a solid block, the entity then gets pushed out of the block according to the usual rules for entity collisions. This can cause it to be expelled in a direction other than the direction it was facing, which may be inaccessible to the player.

Steps to reproduce:

1. Download the attached world "MCPE-126082 Paintings bug.mcworld".
2. Make sure you're in Survival mode.
3. Punch all 4 paintings on either side of the 2 walls, observing where the painting items end up.

Expected results:
All 4 painting items are spawned in the block the painting was in and fall to the floor.

Observed results:
For the paintings on the east- and south-facing walls, the items are spawned as expected and fall to the floor.
For the paintings on the west- and north-facing walls, the items are spawned in the walls they are attached to and, depending on the configuration of blocks in the neighborhood, are expelled to the side or upward until they find an air block or partial block to be in.

Impact:
When this bug occurs, the painting items often end up in positions where the player can't see them. Frequently, the player will believe the painting broke without dropping anything. Even if they suspect this bug has happened, it's difficult to predict where its item entity ended up because the logic that determines where it will go is complicated. And even then, the item could ultimately be pushed into flowing water, lava, a cavern, or an inaccessible void in solid rock and thereby be permanently lost or destroyed. So the impact is that the player can lose their property.

But the cost of this bug is exacerbated in many cases because players typically like to choose which art they're displaying by repeatedly placing and breaking the painting until they randomly get the art they want. When this bug occurs, every attempt will cost them another painting item.

Original description:

Painting when placed in certain areas will break behind the wall and spawn above the wall, sometimes causing them to disappear