Entity shadows not working on non-block models.

An incomplete list of affected blocks are:

• all top slabs and bottom slabs, full slab blocks work fine
• all fences, fence gates and walls 
• all upside down and right-way up stairs
• all trapdoors (though the shadow is still visible on the block underneath)
• all anvils
• all pressure plates
• all heads
• all chests
• snow layer
• grass path
• composter
• cauldron
• enchanting table
• scaffolding
• end rod
• brewing stand
• lectern
• bell
• campfire
• lantern
• hopper
• daylight detector

Essentially any block without the block/block model has been affected. Some of the blocks on this list emit light and I was unsure that they even had shadows in the first place but since you can see your shadow on glowstone, I'm going to assume so.

Additionally, with some blocks (such as the shulker boxes and slime blocks), the semi-transparent shadow will replace the texture of the block in that place, making it possible to see through the block.