Divi image links don’t have a title attribute set and there isn’t a way to set them using the Divi UI.
Code Examples
Good
Even though there’s no title or text set in the link in this code, it will still supply a meaningful label when it’s click event is sent to GA by using the title text in the image’s HTML.
<!-- Note that the image's title and alt attributes are set. -->
<a href="https://www.elegantthemes.com/preview/Divi/wp-content/uploads/2014/04/beaten-path.jpg" class="et_pb_lightbox_image" title="">
<span class="et_pb_image_wrap ">
<img loading="lazy" src="https://www.elegantthemes.com/preview/Divi/wp-content/uploads/2014/04/beaten-path.jpg" alt="The Beaten Path Alt Text" title="The Beaten Path Title Text" width="auto" height="auto">
</span>
</a>

Bad
This code usually generates a “(not set)” label in Google Analytics when it’s tracked. It’s because the image’s title and alt text are blank or don’t exist at all.
<!-- Note that the image's title and alt attributes are NOT set. -->
<a href="https://www.elegantthemes.com/preview/Divi/wp-content/uploads/2014/04/beaten-path.jpg" class="et_pb_lightbox_image" title="">
<span class="et_pb_image_wrap ">
<img loading="lazy" src="https://www.elegantthemes.com/preview/Divi/wp-content/uploads/2014/04/beaten-path.jpg" alt="" title="" width="auto" height="auto">
</span>
</a>
Live Demo Examples
The plugin makes the above possible is the Link Helper Divi plugin. Visit the repo on GitHub and download or fork your own copy.
Sample images and code above provided by Divi’s Image Module page.