When you cannot find a visitor you can should check the filters and the search criteria.
Filters
When you cannot find a created visitor first step is to make sure to check the used filters and extend the search criteria.
Validity
By default the overview shows the visitors/transports which are valid today. By extending the date range you can find visitors who become valid in the future or were valid in the past.
Created
A helpful filter to use is the created where you can see all visitors/transports created in a certain date range. This typically helps troubleshooting why you cannot find a visitor. It can be a profile or a validity mismatch for example.
Blocked
By default all filters exclude Blocked visitors/transports. To find these back make sure to adapt your filter to search for these visitors.
Search text
When you want to search on specific keyword make sure to extend your table to include the fields you want to search on.