Hi, for all themes integrated with page builder, like Divi in my case you have to translate the css class. Example : . myclass img to .myclass.
În Divi theme if you put a custom class to single image module, Divi adds img at the end, like .myclass img, you can not put that in the plugin admin, because will not be recognized. The solutions its a jQuery script, you can put this script în page like an html module or you can put this în global script section în Divi, or other page builder.
<script>
jQuery(‘.myclass img’).addClass(‘.myclass’);</script>
Done.