Hello,
The mobile menu in the mobile panel required a mobile menu element in the header to work properly. So, I added the mobile menu element to the header and hid it using custom CSS, and then the mobile panel menu works https://gyazo.com/df3080f993530889ace247182486590a
Let me know if you want to hide the mobile menu in the header for the mobile device and keep it in the mobile panel only.
Regards