Hey Nicole,
This is possible in case you are using a Third party payment gateway in your event to collect online Payments - For example - Paypal.
In this case, when the invitee clicks the Finish button during the registratiion process, he is taken to the Third party payment website where he gets 20 minutes to complete the payment.
During these 20 minutes, the Cvent system marks this invitees as "Registered" and assigns a confirmation number to the registration.
If the invitee completes the payment, he stays registered in the event. However, if the payment is declined or is no completed due to any reason, the invitee goes back to "Visited" status and the confirmation number becomes invalid.
Here is the article link for the same -
Why is my registrant in "Visited" status when I know they registered? (https://app.cvent.com/Subscribers/Account/default.aspx?page=BE132BFF-ADD3-41F2-BCC9-4DBCE592E47E&targetPath=apex/CommunityArticle?id=000054853)If you can share the Event and Invitee name, we can certainly get you more detailed information.
Regards
Ankita Gupta