Mobs in 18w43b are invisible

So, I was super excited to see what 1.14 may look like. I wanted to see the pandas, most notably. I looked at the nearest Jungle Pyramid, and saw nothing, set aside the new textures (and some bamboo. No pandas. I try

/summon minecraft:panda

. Says 'Summoned New Panda'. Nothing happened though. I reasoned that the /summon was set to a default of the world spawn. then I tried

/summon minecraft:panda ~ ~ ~

, but got the same thing. I want to see those pandas!!!