We anticipate issues with the classic Divi Builder in the future as the developer, Elegant Themes, will be focusing on the latest Divi Builder experience. As posted at their website:
This update is incredibly important for so many reasons, the most important being that it unifies the Backend Builder and Visual Builder experience and code base. This means that Divi users will not have to choose between two disparate experiences, but instead can feel comfortable building within the post editor and on the front end alike. This also means that our development team can focus on a single code base and iterate more quickly and efficiently. This will result in adding new features twice as fast and dealing with half as many bugs along the way. This is a critical transition for the community and for our team.
For more details and instructions, please visit: https://intercom.help/elegantthemes/en/articles/2509618-the-new-divi-builder-experience
We recommend our users to use the latest Divi Builder experience (if you have not done so) to avoid potential issues arising from future WordPress core updates. The latest Divi Builder experience interface is distinct from classic Divi Builder. You would be able to know which version you are using based on the interface – see image below showing the latest Divi Builder experience. The latest version utilises circled plus icons for adding elements.