Hard to drag after changed the list by customized

[AbelLai]

I have a list like this code#1:
`

` Now, I have a feature is that I selected one or more li and click a button, the selected lis would be nested in a li. For example, I selected the list_one and list_two, after click a button, the list would be this code#2: `

` After changed the list like code#2, the items in list will be hard to drag. If I drag the items in the list first, and do the operation like above I said. It is normal to drag. I don't know why.

Any guys have this issue?

The version in my project is v1.3.5.