Returned payment.requestId no longer reflects the X-Request-Id

The requestId field of payment objects returned from createPayment and getPayments used to reflect the X-Request-Id specified when creating the payment.

However, the behavior in the sandbox today no longer appears to reflect that; in fact, the same (random) requestId appears for all objects returned from getPayments.

Is this a bug?

We depend on the X-Request-Id that we sent to be reflected in the payment object, essentially as a foreign key that we use for internal bookkeeping.