If you edit any content ( here I used an article ) and preview it, the preview will fallback to legacy design.
- Edit vendor/ezsystems/demobundle/EzSystems/DemoBundle/Resources/views/full/article.html.twig and change the h1 line
- Edit ezpublish_legacy/extension/ezdemo/design/ezdemo/override/templates/full/article.tpl and change the h1 line
- Clear the caches
- Make sure your frontend is not in legacy_mode.
- Login in frotend
- Create the new "Article #001" article
- Open the published "Article #001"
- Make sure you see "# TWIG:" in the article header
- Edit "Article #001" and preview it
- Confirm now you will see "# LEGACY:" in the article header