Question Adding script to sub blend tree

So I used a blend tree with a script to randomly have my idle jump to 'twitches' when the idle has played after a set number of seconds.

I wanted to do the same thing to my movement blend tree that goes from slow walking to run cycle when my character is moving forward. When I add a BlendTree to my animation states in my movement blend tree I noticed there were no add behavior options as I saw in the blend tree I created in my base layer.

Can you not attach a script to blend tree nodes after you create them as sub-blend trees?

I also noticed the script I attached to my idle blend tree disappeared when I attached the blend tree via connections to other states but when I disconnect all the other states the script shows up again. Its still working but I don't know why visual the inspector no longer shows you the scripts you attached to the animation state. Is this a bug?