nesting

Hi, thank you for this great plugin…
I had follow steps on this link:

https://ww.wp.xz.cn/support/topic/nesting-problem/

and it was very helpful, but I have a little problem with some sort of nesting like this:

Level 1
subject 1
subject 2
subject 2-1
subject1 2-2
subject 3

the problem is, with subject 3, it’s displayed in some place out of the level 1!

Thank you