2012 Transactional replication not delivering new articles
According to Define an Article:


  If the publication has existing subscriptions and sp_helppublication
  returns a value of 0 in the immediate_sync column, you must call
  sp_addsubscription to add the article to each existing
  subscription.


After executing sp_addarticle, execute sp_addsubscription to add the article to each existing subscription.  Then generate a new snapshot.  The Distribution Agent should then copy the schema and data for the newly added article to the Subscriber(s).