I am looking more closely at the data structure and it appears that when the form is submitted we get an unlinked recurring contribution series and membership. Is this by design or user error in configuration?
the details - the civicrm_membership table field 'contribution_recur_id' does not seem to have the recurring ID updated from the recurring profile the webform created
Is this how people are gaining the functionality? https://github.com/adixon/ca.civicrm.contributionrecur
Drupal 7 / up to date webform_civicrm and civi