Because it hasn't been published yet.
A brand-new workflow is in Draft. While it's a draft it has no board, no Kanban, and can't create real deals — and it doesn't even appear in the Input Hub navigation. Only published workflows are listed there. This is the most common "where did my workflow go?" question, and the cause is almost always the same: it's never been published.
The fix
Publish it once. Build your steps and items, then click Publish (on the History tab, or via Drafts & Versions if your account has that feature). After the first publish:
- the workflow appears in the left navigation,
- you get its Kanban board,
- and you can create and test deals and switch between views.
"But I want to test while I'm building it"
That's exactly what the first publish unlocks. Publishing takes an immutable snapshot, and existing deals lock to the version they were created on — so you can keep editing the workflow afterwards and re-publish without disturbing deals already in flight. Your edits only affect new deals.
For the full detail, see Workflow Settings, Publishing & Self-Registration and Order Workflows.