Before you can activate a market, you need to have shipping rates for all countries and regions in that market. Please go to Settings > Shipping and delivery to check if a shipping rate is configured for that market.
As per what @AvadaCommerce recommended, I wanted to check up to see if you managed to properly add shipping rates for your international regions in order to activate markets?
For reference, you can use our guide here on adding shipping rates to your Shopify store. If there is anything else I can help you with, please let me know.
Dirk | Social Care @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog