Need help with Update Block error - Operation Failed, 404 Resource Not Found


Ok so I'm building a real-time inventory integration, to show P21 inventory data on our Magento website.


I'm querying P21 for inventory data

Fetching Magento for product and stock data table

Then doing an Update block to update the stock data table


Any idea why it might say Resource Not Found? See attached screenshot. Was told to join the Magento stock_item table to the product table using RESTVAR_id to entity_id.