We are running Piwik version 2.16.0 and generate monthly reports of Actions-Page URLs with the flat=1 option to present a list of the top pages viewed by users.
With our announcements website where subpages hits are higher than top level hits, our report includes an aggregate count on a subfolder that looks like this:
html/bulletins/eb/eb2001/ - Others html/bulletins/eb/eb2016/eb16_006.html ... Others
when this line appears in the report, its URL incorrectly refers to the item on the next line. Then, all following line items have URLs point to the next line item also. The content of this folder is similar, if not identical, to folders for other years.