When you edit the Theme Builder sections and see this message:
“Sorry, the content area was not found in your page. You must call
the_content function in the current template, in order for Elementor to work on this page.”
WordPress permalinks needs to be flushed. Go to WP Dashboard – Settings – Permalinks and hit “Save Changes“. When the page is refreshed, your permalink structure has been reset (or flushed).
Now edit the Theme Builder sections with Elementor