Shopify + ShipStation API Integration Expert Needed (Checkout Shipping Rates Issue)

We are looking for an experienced Shopify developer with deep knowledge of ShipStation integrations to troubleshoot and resolve a shipping rate issue on one Shopify site. We use ShipStation only to return live shipping rates during checkout. This setup is working correctly on multiple Shopify sites, but one site is not displaying ShipStation as a rate provider, despite appearing connected. This role requires hands-on technical investigation, API understanding, and coordination with Shopify and ShipStation support to identify and resolve the issue. Current Situation ShipStation is used only for checkout shipping quotes ShipStation is not used for fulfillment, labels, or packing slips The Shopify ↔ ShipStation sync appears connected on the ShipStation side (needs verification) The ShipStation app is installed and connected in Shopify (needs verification) In Shopify → Settings → Shipping and Delivery → Shipping Profiles, ShipStation does NOT appear as a rate provider in Shipping Zones The same configuration works on other Shopify stores Scope of Work Audit Shopify shipping settings and shipping profiles Verify ShipStation app installation and API connection Confirm ShipStation account settings for rate calculation Identify why ShipStation is not appearing as a rate provider Interface with Shopify Support and ShipStation Support as needed Implement and test the fix to ensure rates return properly at checkout Provide a clear explanation of the issue and resolution Required Experience Proven experience with Shopify shipping rate providers Strong working knowledge of ShipStation + Shopify integrations Experience troubleshooting checkout rate calculation issues Familiarity with Shopify Shipping Profiles and carrier services Comfortable working with APIs and platform support teams Clear communication and documentation skills Nice to Have Experience with multiple Shopify stores under one ShipStation account Past experience resolving ShipStation rate visibility issues Shopify Partner or ShipStation integration experience Project Type One-time troubleshooting and fix Potential for future Shopify integration work To Apply Please include: Your experience with Shopify + ShipStation integrations Examples of similar shipping or rate-calculation issues you’ve solved Your approach to diagnosing this type of issue