Hi Douglas,
This behavior is by design, Work column is locked at the project level, as this is a value that rolls up from subitems. We can suggest adding at least one task for each project, that way you will be able to update Work field from the leaf item.
For further clarification, please join our Intermediate Q&A webinars (see the link-> http://www.clarizen.com/resources/online-demo.html#second ).These are great resources for free consulting with our Customer Success Managers and visual answers to your questions. One of our experts will be able to explain it in detail as well as discuss your use case and suggest best practice advice accordingly.
All the best,
Diana