It’s hard to help without seeing the code from the parent and child LiveViews, but I have a question: is there any good reason to use LiveViews for implementing the widgets instead of a LiveComponent?

It looks like you’re running into some race conditions with your LiveView updates. I think the issue is that push_state is happening before the ui_state is ready. Try splitting the logic for updating the socket and calling push_event into two separate functions. For example:

def handle_async(:load_ui_data, {:ok, fetched_data}, socket) do
  %{ui_data: ui_data} = socket.assigns
  ui_data = AsyncResult.ok(ui_data, fetched_data)
  socket = assign(socket, :ui_data, ui_data)

  send(self(), :update_timer)

  {:noreply, socket}
end

I get why you’re nesting LiveViews, but if it were up to me, I’d go with a LiveView + LiveComponent setup and a central broker. By consolidating state updates in a single place, you can more effectively manage transitions and reduce the chance of race conditions. Furthermore, using fewer LiveViews and more LiveComponents with a central broker reduces the number of processes the application needs to open, which lowers resource consumption and ensures better scalability as the application grows.