Since you are creating the TreeView programmatically the issue is most probably related to the data you are binding it to. Unfortunately I don't have the data you are using, so it's impossible for me to reproduce the issue on my end.
What I would suggest is to check whether the GetProjectData method returns all the nodes you are expecting. Also, you can try substituting RadTreeView for the ASP.NET TreeView and see whether it binds correctly. If it does, then the issue is caused by RadTreeView itself and we will do our best to resolve the issue.
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