At this early date there seems to be conflicting information out regarding the new blackpearl’s support for Microsoft Internet Explorer (IE) 11.
As of yesterday, the Compatibility Matrix shows IE 11 as unsupported. Yet the New Features List for blackpearl 4.6.9 says it IS supported, and offers this KB article with instructions for a workaround to allow the K2 Workspace and other portals to render correctly in the browser.