Scope
Customers are unable to update subscriptions via portal- RazorPay gateway
Summary
When you have RazorPay integrated, you cannot make any changes to the subscription such as quantity, plan or plan price via the portal. RazorPay does not support any of the above.
If you head to the portal, and change ONLY the shipping address (without changing any of the subscription details such as quantity), you will be able to update the shipping address successfully.