Visitor log count of visits does not agree with Page Views

Hi,

We are investigating under-reported visitor numbers in Piwik 2.16.5. The Visitor log shows 3 visits while the Actions → Pages report shows 2.

Clicking on the row to view the Segmented visitor log where the number of pageviews is “2”, shows 3 visitors.

Any ideas? Clicking other rows, the number of visitors never quite adds up to the pageviews shown in the report.