Symptoms

You may notice the following issue with OOO settings in the 4.6.9 worklist control: it is impossible to set OOF exceptions for user without K2 server level Export rights because process to select not being shown in the dialog.
This functionality for the same user works in K2 workspace , but it does not work in K2 worklist control and in K2 workspace webpart.
 

Diagnoses

You see this behavior because both K2 worklist and K2 workspace webpart make use of SourceCode.Workflow.Management API which requires Workflow Sever Export rights. Using Internet Explorer Developer Tools it is possible to see related exception in response body:

System.ExceptionUser K2:DENALLIXChris has insufficient rights to perform action GetProcessFolders. Minimum of Export rights are required to perform this action.SourceCode.HostServerLib at SourceCode.Workflow.Management.WorkflowManagementServer.GetProcessFolders() at SourceCode.Forms.Utilities.FormsHelper.GetWorkflowResults(Strings] targetNames, ResultTypes resultsTypes, ResultFlags resultFlags) at SourceCode.Forms.Utilities.FormsHelper.GetItems(ResultTypes resultTypes, ResultFlags resultFlags) at SourceCode.Forms.Utilities.AJAXCall.GetItems(String targetType, String targetId, String resultTypes, String resultFlags) at SourceCode.Forms.Utilities.AJAXCall.ProcessRequest(HttpContext httpContext)

Granting server-level Export rights which allowing the user to deploy/export processes to all users in order to give them an ability to configure exceptions for OOF may not always be acceptable.
 

Resolution

This is a known issue in 4.6.9 which has been addressed in 4.6.10 where number of issues with Out of Office Control has been solved including this one.
Following issues with Out of Office Control were resolved in 4.6.10:
1. Unless you are a K2 Administrator, you are not able to select a process to configure an exception rule.
2. If your process is located in nested folders, your process name is one of the folder names.
3. If your process is located in nested folders, your selected activity name is the last folder name.
4. (Only the very first Time) if you configure an exception, and edit the exception, only the exception name is returned. The tree view is empty, and the user configured is also empty.