To reproduce: use the attached sample project and follow the steps:

1. Filter by "Jo".
2. Press the "Refresh" button.
3. Press the "Clear Filter" button.

Note: if there is no applied filter when rebinding, the nodes order is correct. Please refer to the attached gif file.

Workaround: clear the filter before setting the DataSource property and restore ethe filter afterwards:
string filter = this.radTreeView1.Filter + "";
this.radTreeView1.Filter = "";
this.radTreeView1.DataSource = dt;
this.radTreeView1.DisplayMember = "Name";
this.radTreeView1.ValueMember = "Id";
this.radTreeView1.Filter = filter;