What does it mean when Original Source Type is "Web page visit"? It seems to say the lead was created without filling out a form or being imported. They're not anonymous leads, because they have email addresses and other information in the records. We have contacts being created in both ways on the same landing page.
I'm seeing this too - they do fill out a form to become known, but are tagged with either Web Form Fillout or Web Page Visit. No rhyme or reason that I've been able to figure out.
The picklist values seem strange to me, too - are the below the standard values? I've inherited a disaster of an instance so am trying to troubleshoot
Web page visit
Web form fillout
Web link click
It means that the first recorded action for the record was a Web Page visit recorded by Munchkin. It might be the case that the initial activity was pruned since the activity was more than 90 days ago and is no longer visible. You can check by choosing a custom view for the activity log and switching from active to archive.