[Theme:MistyLake] Mobile Menu Button Not Showing.

I have a custom child theme for Misty Lake I use for my site.

The menu button isn’t showing in the mobile view. The links will appear and then disappear when the page first loads, but the button to expand the menu never shows up.

Site: https://www.ironteethserial.com/

I tried switching back to basic Misty Lake and removing plugins but neither helped.

Any assistance would be appreciated, thanks.