I made a report on area effect clouds a few months back and when I went to check it still happened in 15w51b (it does) I noticed the shulker starts z-fighting with the falling sand, this never previously happened and yes I know that I could make the shulker invisible but that's beside the point.

Use this command to reproduce

/summon AreaEffectCloud ~ ~1.125 ~ {Radius:0.5f,Duration:2147483647,Effects:[],Particle:"take",Tags:["Block","BlockController"],Passengers:[{id:"Shulker",Invulnerable:1,NoAI:1,Tags:["Block"]},{id:"FallingSand",Block:"minecraft:stone",Time:1,Tags:["Block"]}]}