Shopify can't find products that are not in my primary 'market'

[NanoDan]

I have a store with Australia set as the primary market.

I have activated South Africa as an additional market.

When I create a Product listing in Shopify, the default condition is that it sets the market for the product to my primary market 'Australia'.

If however I change the market to 'South Africa' Shopify can no longer find the product. I have created a landing page with a buy-now button that is linked to a product with South Africa set as its market. The buy-now button won't work because Shopify thinks the product doesn't exist.

If I change the settings for that product so that its market is now 'Australia' - Shopify can find the product and the buy-now button works.

This has me pulling my hair out. Shopify is supposed to allow you to sell in multiple markets.

Why can't I change the 'market' for a product to anything other than my primary market?