Are you using the runtime experimental demo or inside an editor window? If you're on Runtiome, don't forget to add an EventSystem component next to your PanelRenderer otherwise no events will be sent to your VisualElement hierarchy.
Can you clarify this? In the Panel object that was created, there is (under the UI Elements menu) there is a Panel Renderer and an Event System component on the object. Is there any configuration that needs to happen between them?
There shouldn't be, just make sure you have the correct Event System (it's named the same as the default Event System). It's the one without a proper icon.