Have you configured structure similar as below?
This is 4 level deep nesting and Visual Composer doesn’t allow this when it exceeds to 3 – due to technical limitation WordPress core has put on shortcodes.
Just to demonstrate that, here’s a video I’ve made with default Visual Composer elements where I’m trying to place Pageable Container element.
Did you notice how it is not possible to use Container elements inside another container? See another video that explains more details here – https://wpbakery.atlassian.net/wiki/pages/viewpage.action?pageId=4030521
In Ultimate Addon elements, we allow you to use container elements inside another container so you can at least design the page. However – this disables the drag – drop feature for such structure.
So – you are recommended not to use deep nesting. However, if you still use deep nesting while designing of your pages, the drag – drop might not work as expected.