Why OnEntryInitialized is not called for TreeView?

I use TreeView, when items are generated, OnEntryInitialized is not called

Is your TreeView displayed in the UI correctly?
Are the entries actually generated? (despite the event not being called)

It’s probably best if you show some screenshots of how you’re using the treeview.

Just a quick side note: for child entries to be generated you need to implement the function “On Get Item Children” which can be found on the TreeView if you select it in the designer and scoll to the bottom of the Details panel.