Thanks for the link.
Cerauno’s responsive menu works OK on the demo and on my self-hosted test site, so there might be something specific to your site causing the mobile menu to stop working.
Here are some troubleshooting steps to try:
I see you’re using a child theme. Try activating the parent and see if the mobile menu works. If so, try temporarily removing files from your child theme one by one, checking your site in between each, to find the culprit.
If that doesn’t solve it, try temporarily deactivating all your plugins. Does the problem persist? If the problem is gone, reactivate your plugins one-by-one, testing the mobile menu in between each, to find the conflict.
