YMM & Divi Incompatible?

I had YMM working fine on a previous iteration of this website. I’ve installed the latest version of Divi and used the new Theme Builder feature to build the WooCommerce pages. Ever since doing that, the YMM plugin doesn’t seem to be working.

At first it wouldn’t work at all, it just returned random results to everything.

I uninstalled and then reinstalled the plugin. At first, it would find individual products (when all 3 options were selected) but if you only select the Make or the Make and Model and then Search, it would return all products in random order.

Since then, it has stopped even finding individual products. Now the only product that it can find is if you select “Iveco, Daily, {any year}” but for all other selections it returns a full list of all products in random order.

I did have a horizontal and a vertical search on every page with the visibility set so that only the vertical would display on phone, and only the horizontal on tablet and desktop. I wondered whether the two were conflicting with each other even when one was hidden, so I removed the vertical one, but I still get the same odd behaviour.

There are three templates – the shop “homepage”, product categories/search and individual product pagees – that all have the YMM search included. Does each of these work independently of each other? Is that causing a conflict?

The page I need help with: [log in to see the link]