Thank you for contacting us.
This seems like something in configuration of the RadMenu. If you give a name to the MenuItem, but it is not presented in the DOM tree then it is expected that Test Studio can't find it by name. Maybe you should click first on the menu so the MenuItem is added into the DOM with its name?
After finding the RadMenu and clicking them you should also refresh the DOM tree or the RadMenu itself.
Here is an example against our demo site:
RadMenu myMenu = ActiveBrowser.Find.ById<RadMenu>(
RadMenuItem myItem = myMenu.AllItems.Where<RadMenuItem>(_a => _a.Text.Contains(
RadMenuItem myItemTable = myMenu.AllItems.Where<RadMenuItem>(_a => _a.Text.Contains(
Here I find the items by its text.
Hope that helps.