Dhtmlxtree expand child nodes showing empty space and onscroll displaying child elements

Whenever I drill down through the hierarchy of the dhtmlx tree we are able to see the child node elements but some times child nodes are showing empty space instead of elements. whenever we scroll up then we are able to see the visible nodes.


Please, make sure that all your nodes have unique IDs.
If the problem still occurs for you pleas,e provide a complete demo or a demo link, where the problem can be reproduced locally.