Parts of DCWorkflow management UI are broken (and may have been for a long time), so I have documented a workaround (monkey patch) documented in this issue.
If you add/remove/rename states, transitions, worklists, variables, or permissions for a workflow definition TTW, you are going to find that most of the top-level tab links on the next page of that workflow definition will yield 404 errors, unless you browse via ZMI breadcrumb off the ZMI page you are viewing.
Oddly, I've found very little to corroborate this issue in searching, so I'm documenting it here as well.
I am not super happy to resolve via monkey patch — as I am unclear on whether the redirect behaviors I implemented are the simplest solution to the problem in ZMI (vs fix in DTML). But this "works for me" to make authoring a new workflow TTW workable.