Mobile View with Child Theme

I’ve just switched over from the parent to the child theme and everything on a computer screen is exactly as it was before. But when I view on the mobile screen the main menu icon (top left) has disappeared (it was there and working when using the Parent theme). I’ve checked my settings and I have mobile menu enabled.

The site also has a white strip down the right hand side of all the pages, which causes the pages to slide from side to side (as well as up and down). This also didn’t occur with the parent theme.
*Edit: the white strip seems to relate to the Site Logo Margins settings – I’ve set each of these to 0 and the white strip remains but it’s a quarter of the size.*