can you disable Autoptimize so i can take a closer look.
Can you also confirm the Sticky Nav is set to ON – as theres an separate mobile and desktop options.
In Customizer > Layout > Header –> Mobile Header – can you enable Sticky.
The TOC you will need to speak with Elementor – as it uses Absolute Positioning on Mobile devices which is why its not sticking. Not sure why it would do that…