So didn't the user reach page 1 at all?
The variable LASTPAGE is the last page that has been submitted by pressing the "next" button. So, if only the page was opened, and then closed, the LASTPAGE is 0. The answers to page 1 have not been submitted in that case. The TIME*** variables shall also be empty in these cases.
What does it mean?
It means that you have most likely enabled storing empty interviews in the project's privacy settings. Usually, SoSci Survey will drop interviews if only the first page has been opened (this might also be a search engine that scans the web or someone clicking the link twice or reloading the welcome page), but there are circumstances when it is useful to also store these empty datasets.