I have a hard time setting up URL alias patterns when it comes to taxonomy terms. Especially, I'm stunned that in the Replacement under Content Paths, a term reference field shows just one flat item [node:field_term_name], rather than an expandable set of taxonomy-related tokens. This is the way it used to be (as in the screenshot here: Pathauto url of term for node?) Have things changed or is it a bug?
Enabling the Entity_Token sub module does help with this issue, however, you need to add a "Term Reference" type field to any of your content types in order to see your taxonomy vocabulary be listed as one of the replacement tokens. In my case, I had enabled the entity_tokens module but I was still not able to see my vocabulary as one of the replacement tokens. Then I added a new field to my "basic page" content type. The field type I added was "term reference" and I selected my custom vocabulary as its default vocabulary. This resolved my issue.