The index/loop also seems to have been rewritten completely a lot more optimised, perhaps he has been updating things for the better but didn’t look or simply forgot to check these parts or so.
I had to chance a lot of my code from my child theme as a lot got changed to the actual pages so it seems and even weirder I had to change the version from my child theme from 1.0.0 to 1.0.1 or the style had various errors.
But yea the menus/sidebars do NOT work on mobile or resized resolution on your browser and the dropdown/child pages are not appearing in the normal view either.