Missed deferral opportunity - pre-tax and after-tax?

Our plan allows both elective deferrals and after-tax contributions.  If an otherwise eligible employee was excluded from participation in the plan, I understand we need to provide a QNEC for the missed deferral opportunity and the missed after-tax contribution amount, plus applicable earnings, and the related missed match, plus applicable earnings.  If no one has ever made after-tax contributions under the plan, do we just use the ACP attributable to match for the employee's group?

The missed after-tax would only be if there was a mandatory component