1. By default, the mega menu category will not work on mobile. At this moment, mega menu category only available on desktop view.
2. Can you please send me the post URL that the share counter doesn’t work? Also, for the social share counter will update the counter every 24 hours.
3. You can find it here https://wordpress.org/plugins/fb-instant-articles/
4. May i know what kind of tools that you use for that testing? so i can replicate it on my side.