Tokens for taxonomy term parents in Pathauto
I just tested the tokens that I suggested in the comments with field_tags on articles and it works perfectly, no idea what your problem is, make sure you use the latest versions of pathauto and token.

Token: /articles/[node:field_tags:0:entity:parents:join-path]/[node:field_tags:0:entity]/[node:title]

Tag hierachy: A > B > C

Alias for an article tagged with C: /articles/a/b/c/pathauto-test