Find Children returning exception for windows app

Help Studio
1

I’m trying to use Find Children to get all nodes in a windows app tree view - have to navigate to each node & do some processing - problem is Find Children is returning nothing or FindElementException as below, tried both wasy passing an Element or Selector - I’m new to UiPath any help or hints much appreciated.

18.4.3+Branch.master.Sha.9888b477be8d3ec8a832306fc59c34ba6edad108

Source: Find Children ‘outline item’

Message: Error HRESULT E_FAIL has been returned from a call to a COM component.

Exception Type: UiPath.Core.FindElementException

An ExceptionDetail, likely created by IncludeExceptionDetailInFaults=true, whose value is:
UiPath.Core.FindElementException: Error HRESULT E_FAIL has been returned from a call to a COM component. ----> System.Runtime.InteropServices.COMException: Error HRESULT E_FAIL has been returned from a call to a COM component.
at UiPath.UiNodeClass.FindAll(UiFindScope scope, String nodeID)
at UiPath.Core.UiElement.FindAll(FindScope scope, Selector selector)
— End of inner ExceptionDetail stack trace —
at UiPath.Core.Activities.TaskAsyncCodeActivity`1.EndExecute(AsyncCodeActivityContext context, IAsyncResult result)
at System.Activities.AsyncCodeActivity.System.Activities.IAsyncCodeActivity.FinishExecution(AsyncCodeActivityContext context, IAsyncResult result)
at System.Activities.AsyncCodeActivity.CompleteAsyncCodeActivityData.CompleteAsyncCodeActivityWorkItem.Execute(ActivityExecutor executor, BookmarkManager bookmarkManager)

image