If you see the 'incomplete' status beside a reservation, this is what you need to do:
If a guest starts going through the Guest Portal, but doesn't complete it, their reservation status will show as 'incomplete.' At this point, it's important to get in touch with the guest and encourage them to complete the Guest Portal.
Consider setting up reminder messages to be sent as part of your message flow. That way, your messages will go out automatically and only to guests who have yet to complete the Guest Portal. Use wording like "to confirm your reservation, please complete the Guest Portal" and "you're almost confirmed, please complete the Guest Portal," etc.
Be sure to include their general Guest Portal link (as found in the "Guest Portal Link" box within their reservation details) so that the guest can be directed to their next step and through their next steps, accordingly.