Symptoms

When opening the SharePoint list and traversing to the K2 Workflows section, the logged on user sees a message 'the current logged in user does not have start rights to the selected workflow'.
even though the user is a member of SharePoint owners and members group.
 

Diagnoses

Explicitly granting ‘Start/View’ rights to the workflow for a specific user does not present the issue.

Closer observation would reveal that the incorrect group names were specified in the workflow rights configuration.
 

Resolution

Double check to make sure you have the correct group names specified in the workflow rights configuration for the workflow in question.