DLP - Why some Endpoint incidents do not show a source path?

I have noticed that some of the incidents generated , do not show a path for the source file, only destination. In other words, if an incident is generated because there was a file copied from an internet site or a SharePoint site into a USB drive. The incident details do not show a path for the file source, just the file name and destination path, but no source path... Any guidance on this will be appreciated.

 

DLP 11.6

 

Thank you.

 

Amit