Granting Add-on/IAP entitlements to test users fails in the Developer Dashboard. The error occurs when attempting to add an entitlement via the test users management page, resulting in a GraphQL mutation failure with error code 1675030 ("Error performing query"). The issue originates from the Relay network layer, specifically in RelayGraphQLRequestUtils.createErrorFromPayload, indicating a server-side rejection of the entitlement grant operation.