Summary:
Paintings can no longer be placed on the following blocks:

• Chest
• Furnace
• Blast Furnace
• Smoker
• Bee Nest
• Beehive
• Jukebox
• Note Block
• Monster Spawner
• Lodestone
• Enchantment Table
• Piston
• Bell
• Bed
• Brewing Stand
• Hopper
• Conduit
• Sign
• Banner
• Beacon
• Lectern
• Cauldron
• Campfire
• Shulker Box
• Barrel
• Daylight Sensor
• Command Block
• Structure Block
• Jigsaw Block

Steps to Reproduce:

1. Place the listed blocks
2. Attempt to place a painting on them

Observed Results:
The painting cannot be placed.

Expected Results:
The painting should be placed.

Original Description:
To make a secret passage way I use signs on walls (I put a screenshot of what I'm talking about) and I normally can put paintings over the signs. Now I can't.