Unexpected inventory value returned by Shopify Admin GraphQL API

I encountered an issue while using the Shopify Admin GraphQL API. Here’s my setup:

  • I fetch all ProductVariants’ inventory levels every 10 minutes
  • Compare them with another data source
  • Adjust if there are any differences

Today, I noticed a strange behavior with one product:

  1. The inventory should be 5, but the API returned 206 (I have the original JSON response saved)
  2. My system automatically adjusted it (reduced by 201)
  3. 10 minutes later, the API returned -196
  4. The system automatically adjusted again (added 201), bringing it back to 5

The main concern is: Why did the API return 206 as the inventory level? This caused incorrect adjustments and made the product unsellable.

I have attached the inventory adjustment history and the original GraphQL response data for reference.

Has anyone encountered similar issues or can explain what might have caused this behavior?