When customizing your Workflow, you may notice the Task and Task User steps are missing:
This is how it should look:
This is a known issue, however it is expected in the K2 Product at this time. The development team are looking into fixing this in the Product at a later stage.
1. Select the User Task step
2. Drag the Task > ID field into the task instruction text box:
3. Select and copy the field
4. Switch back to the non-Task step, and then paste the field, for an example see below: