Symptoms

Picture Libraries in SharePoint 2013 are now supported with K2 for Sharepoint 2013 4.6.11. As such, smartobjects can be created against the Library using the K2 blackpearl for SharePoint app and therefore can be used as source smartobjects for list views and editable list views. However, when the image files are displayed in the list view, a link to the image itself is shown rather than a thumbnail or similar.
 

Diagnoses

This was confirmed as a bug in 4.6.11, and an item has been logged for such.
 

Resolution

The following bug item has been logged for this behavior:

Bug 594493: SP2013 - XML Generated for Photo Library SMO Properties Flagging Document as File as Opposed to Image

Please contact K2 Support by logging a support ticket if this behavior is being seen.