Unable to upload documents from pending action items

Summary

Pending action items doesn't allow documents to be uploaded

Content

For New Hire life event, we have requirement to have dependent's SSN card copy as an action item. I set it up as a designation requirement for dependents. However, in self-service, in pending action items work area, employee is unable to upload the SSN copy. There is no URL. What setup am I missing? Any help is greatly appreciated!