I am having what I believe is the same issue as described in Workflow association with the list is not recognized by SharePoint, but the solution there is not working for me.
I have a fairly basic custom list. In SharePoint Designer, from the settings page for that list, I clicked New > List Workflow, and created a very simple workflow. On the workflow's settings page in SPD it indicates that it is associated with my list. But if I click "Open associated list", my workflow does not appear on the list's settings page. I did Save and Publish the workflow, and I also tried closing and relaunching SPD, etc. At no point did I receive any error messages.
If, from the list's settings page, I try to "Associate Existing Workflow", the workflow I created doesn't appear as a choice there either.
What am I doing wrong?