several commands not working

I built a command system in 1.8 that summons FallingSand

{block:command_block}

riding fallingsand riding fallingsand riding fallingsand. Each was a command block with a different command. However, when I opened the same world in 1.9, only the first FallingSand appeared. It wasn't riding anything. Another command in the same map that stopped working was the execute command. Previously, when I spawned a named entity, a series of commands would run relative to that entity. Now it just acts like a normal animal. No commands are being applied to it. Both of these non-working commands have rendered the entirety of my map completely useless. I don't know if these were intentional changes, but i'm seriously frustrated.