An empty list is a disclosure, and the auditor tests it like one.
The common read: Nothing got breached, so there is nothing to report.
It does not hold, and the customer data is not why. DC4 covers identified system incidents that, verbatim, "(a) were the result of controls that were not suitably designed or operating effectively or (b) otherwise resulted in a significant failure in the achievement of one or more of those service commitments and system requirements". The criterion has two triggering conditions, and an incident is in scope if it meets EITHER one.
An automated renewal that stopped producing certificates is a control that was not operating effectively, so the outage it caused is inside the first condition on its own. Harm to customer data is not a condition anywhere in that sentence. An empty list is not a violation either, which is the half most readiness presentations get wrong: the implementation guidance says that if there have been no significant incidents that require disclosure, management may disclose that fact.
So an empty list is permitted, and the question is what it claims. "No identified system incidents" asserts that the entity's own detection and declaration criteria ran across the whole of 2026-01-01 to 2026-06-30 and that nothing they produced met either triggering condition. For each incident that does meet a condition, the criterion asks for its nature, the timing surrounding it, and its extent or effect and disposition. A short period does not lower the standard for the zero.
For example, the auditor requests the pager history, the ticket queue and the status-page record, and the team's answer covers only three weeks, because the retention period is three weeks. The entity cannot support the zero, so the finding is against the description, and the auditor will likely say so in its opinion on the description. Raising the retention to cover the period is one configuration change and one invoice line.

