Recipient groups in a scheduled mail return no recipients.
Creating or reusing a scheduled mail in CiviMail v4.7.31 under Joomla returns no recipients when groups are added to the recipient list. The demo sites are several versions behind and run under Drupal, so can't be used to verify. At this point I'm unsure of where the search takes place, so have a problem debugging it.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information