Everything after version 1.6.4 doesnt work

I have had some issues with this main plugin as I also have the Premium Plugin. The only version I can get working is 1.6.3. Everything after that including the latest update doesn’t seem to work with my product pages. I just get a serious error and the page doesn’t load at all.
Here is the staging site to show the issues. https://www.staging1.elektramagnesium.com.au/shop/sensory-gold-magnesium-cream/

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