Excerpt Text Missing in Email

I use the free version of Mailpoet extensively, but not seen this problem before. I have posts which have text in them and featured images. When I prepare a newsletter and insert the posts normally the title appears followed by an automated excerpt from the text, a read more link and the featured image. I did not need to do anything special to make that happen. I have just edited a site and changed the template from Divi 4 to Divi 5 (By Elegant Themes). The excerpts are not automatically present, just the title, read more link and featured image.

I have a feeling that I have seen this before a long time ago, but not recently. Any clues as to what the problem is?

I checked the options for displaying the post in a newsletter. I cannot see anything wrong there, but I have never changed them in the past.

The site is very lightweight in terms of plugins.