I too have noticed, megamenu has stopped working since the WordPress update. I do not know if was caused by the latest 5.7.1 or an earlier update. All I get is
The top of the megamenu but no text and menu items showing. I have had to put my main site under development and have created a staging site to test, but I am not able to resolve it. No changes were made, so as it worked for previous version, I would expect that to continue.
