Have you disabled the OS setting for collecting that data?

Right click on your taskbar and pick properties from the menu, then in the taskbar properties window pick the Jump Lists tab.

There should be two checkboxes in the Privacy group.  The first one relates to the information captured for the recently used apps section of the startmenu.

The other thing to check is in Start8 itself, on the configure page make sure show recently used applications is ticked.

After changing those I would recommend a reboot as the OS may not start collection until later.

Also be aware some apps which cleanup things such as cookies and history lists may actively wipe the list.