SSE Adding Childs To Some Animations Does Nothing

[tdw2]

For example, in the old creation kit, I could go to Gameplay > Animations > Dwarven Spider, then right click the dwarven spider, hit 'Add Child', and add 'ActionLeftAttack'. In the new Creation Kit for SSE, when I try and add left or right attack to a lot of actors, it simply won't add. What is happening?

 

Here is a GIF of it: http://i.imgur.com/sVRX9H2.gifv

 

As you can see, it's not working for the Falmer. But if I try doing that on a bear, it works fine.

Edited December 22, 2016 by tdw2