Update: This happens when you are given access to your client's store and you try to add any kind of payment from you app. Managed stores don't have access to store's payment APIs. Only the store owner can initiate those. Nothing wrong with the query...

I am using appSubscriptionCreate mutation(  https://community.shopify.com/c/Shopify-APIs-SDKs/appSubscriptionCreate-on-a-live-application-Internal-Server/m-p/748312#M49811 ), with line item being of type - appRecurringPricingDetails. This works fine ...