I'm using CiviCRM 4.7.11 on Drupal. For some time now (not sure how many minor versions) it has not been possible to create reports or to save changes to any reports. The button ("Update Report", I believe it used to say) is missing.
This is the case on my live and dev sites. On the dev site I disabled all extensions which did not help. I can't check on demo.civicrm.org as it is currently broken.