Hi Mathieu,
Thanks for using Syncfusion products.
While using TreeViewAdv virtualization, the treeviewitemadv
will generate only when it come in to view port, this is one of the behaviour
of Virtualization. Similarly, the children treeviewitemadv will generate while after
expanding the parent treeviewitemadv.
Please let us know if you have any queries.
Regards,
Karthik