Issue reading node names from a TVirtualStringTree object

We have a TVirtualStringTree tree for a list of items. It has expandable icons and checkboxes as shown in the image. I can never check the checkboxes. It shows error as "The tree nodes have no check boxes or they are custom-drawn." When I try to read the tree root nodes, it returns me the first node and then the sub nodes of it. But I can't read the root nodes of the tree. Can someone please help me with a proper way to read all the nodes of the tree. I need to also check the checkboxes or click on a particular node.

NOTE: If I record the actions of expanding nodes or checking the check boxes, it comes up as something like below-

let virtualStringTree = Aliases.patients.EthnicitySelectorForm.ViewPanel.EthnicityTree;
virtualStringTree.Click(15, 27);
virtualStringTree.Click(35, 26);