Making featured image the facebook image turned off the variants This post is outdated
So I found out how to make facebook use the featured image by changing the og:image meta field. That seemed to work.
I also figured out from a help article page (https://help.shopify.com/themes/customization/products/variants/show-featured-image-on-product-page) how to display the featured image when the product page is initially loaded as opposed to the first variant being selected and displaying its image. That seemed to work.
But when I made these two changes, something caused the variants in my facebook shop to "disappear" and only an add to cart button is available per product even though there are variants that should be selected.
Does anyone have any thoughts how to re-enable product variants in facebook and yet still display the featured image on load of a product page, and as the main image for each facebook products?