Items stuck in blocks move upwards. This used to happen in a smooth flowing motion, now they jump, one block at a time. This new behavior was most likely introduced in one of the 1.11 snapshots.

Steps to Reproduce:

• Summon a solid box of glass blocks.

• /fill ~1 ~ ~1 ~5 ~15 ~5 minecraft:glass

• Summon an item inside the glass blocks.

• /summon minecraft:item ~3 ~1 ~3 {Item:{id:"minecraft:stone",Count:1b}}

• Watch the item closely as it moves through the blocks.
• Take note as to whether or not items move through blocks smoothly.