Symptoms

It seems that the K2 for SharePoint Designer is not available from a SharePoint list/document library (SP 2010) after upgrading to 4.6.11.
Whenever clicking on the K2 button on the Ribbon bar they receive the following error:
"Error: Required item: Process Designer - ConfigurationManagerData setting not found"
 

Diagnoses

The issue has already been identified in the 4.6.9 version of K2 Blakcpearl and K2 for SharePoint and a TFS item logged.
Based on previous notes it seems that K2 looks for the key in the primary root site collection instead of the Wild Card site collection.
 

Resolution

As a workaround all the K2 features have to be activated on the primary root site collection (the web application's root URL).
After activating the features the error did not occur anymore.