Hello @igscomp,
I checked the case and was able to replicate the problem on a default WordPress using BeTheme.
The issue is caused by the Minify JavaScript Files feature in Frontend optimization >> Javascript. Instead of disabling it, you can use the Exclude from JavaScript Minification option below it and add the script below to the exclude list:
/themes/betheme/js/scripts.js
The menu will appear after adding it and clearing your website’s cache.