Flash not showing anymore after migrated to 1.5.1

I have migrated to 1.5.1 recently, after created the root.html.leex, I have this content in my app.html.eex. But Flash not showing anymore, when I inspect in Chrome, I can’t see the whole section. Any idea?

<main role="main" class="container">
  <p class="alert alert-info" role="alert"><%= get_flash(@conn, :info) %></p>
  <p class="alert alert-danger" role="alert"><%= get_flash(@conn, :error) %></p>
  <%= @inner_content %>

Actually the live one not working, I have this in live.html.leex, but not loading:

<main role="main" class="container here-live-html-leex">
  <p class="alert alert-info" role="alert"
    phx-value-key="info"><%= live_flash(@flash, :info) %></p>

  <p class="alert alert-danger" role="alert"
    phx-value-key="error"><%= live_flash(@flash, :error) %></p>

  <%= @inner_content %>

Any idea?

Issue resolved, those old LiveView files need to change:
use Phoenix.LiveView
use MyHelloWeb, :live_view