[Theme: Emulate] 404 pages with recent WP update

Hi.

I set up a site about 2 years ago using the Emulate theme from Themewoot, who appear to have closed up shop by now.

It was a mobile responsive site, and with a recent upgrade, it appeared to be stuck in mobile mode, even on a desktop. Menus were expanded, things were just..gone.

I found someone else with a similar problem, and the given solution here…
http://wordpress.stackexchange.com/questions/223722/theme-broken-after-upgrading-to-wordpress-4-5-missing-stylesheet

This fixed some of the issues. The main page looks semi-normal again, though it is still missing some elements.

The problem lies in my portfolio pages now, similar to the last comment on the linked page above. I can see the pages in the back end, however, when I open one to view live, it gives me a 404 error.

Anyone have any ideas on how to fix this? What could be happening to make these pages disappear as they are?

The site in question is SidingIndustries.com. In the footer, you can see thumbnails from Portfolio pages. Opening them leads to the 404 errors.

Thank you for any advice on this issue.