Answer
Check the specific view the navigation is built on — if it's a custom-field view (a _CFV), navigation can fail with Invalid Identifier if that view has no custom field currently marked as visible; make sure at least one custom field on the relevant _CFV is set to visible, and confirm you're navigating through the correct base view for the entity (test the view directly with a PL/SQL query first to rule out an unrelated SQL issue). Getting the right view with at least one visible custom field is what resolves this specific navigation error, even when the Lobby element's own data display was already working correctly.