If you are sending multiple documents at once, the counterparty must sign, or as appropriate approve of, every one of those documents.
If they only approve one attachment, the document will still be waiting for completion.
It is also possible that someone in the role of approver is waiting in the signing process in addition to the counterparties that have already signed. In this situation, the document can be signed by everyone and still behave like an unsigned document and be awaiting completion, because approval from one or more counterparties is still missing.