[Zuora developer docs]: when refunding a subscription that is not invoiced separately, the cancel and refund fails unless the Invoice Item Settlement feature is enabled on the tenant. Without it, Zuora cannot split the shared invoice across the linked subscriptions. The same feature gate applies to write-off of outstanding balances on the invoice. Enable Invoice Item Settlement in tenant settings before running cancel-with-refund flows, and set the Zuora-Version header to 211.0 or later when using subscription suspend, cancel, or the newer Orders flows.

Context: Canceling and refunding a subscription fails with 'Cancellation/Refund failed because of the following reason: Invoice is linked to multiple subscriptions. Cancellation was not processed.'