Today I thought I'd try and beat the Ender Dragon with the new crossbow. Sadly when I finally reached The End there was no dragon at all. So then I decided to spawn one. I did the following:

/summon minecraft:ender_dragon 0 100 0
/summon minecraft:ender_dragon 0 100 0 {NoAI:0b, Invulnerable:0}
/summon minecraft:ender_dragon 0 100 0 {NoAI:0b}

The command I used doesn't work as expected and it seems though the dragon takes no effect from the nbt. I was also unable to hit the dragon with any of my arrows. It is invulnerable. I then killed the dragon and summoned a new one. There was no change. The dragon just stayed there. Here are five screenshots taken one second after the other so you can see the dragon isn't moving.

I'm on Hard difficulty.