Employees not able to add dependents when electing benefits

Summary:

I know this question has been asked before, and I followed the advice on the Accepted Answer but it didn't change anything so I'm asking again.

We have several new employees whose dependents cannot be added to coverage. All dependents are entered in People to Cover and all dependents have a birthday, SSN, and gender. All children are under 26. We only get the option for Employee Only coverage. The previous accepted answer was "Verify the relationship start date of your contact is on or before the life event occurred date. If the relationship start date is after you will need to go to the contact record in Person Management and adjust the start date."