I've tried to test v4.7.13 smart groups with relative dates after the bug is supposedly fixed: Is it a bug that Relative Dates are broken in Search and Smart Groups?
- Now, I create an Activity today for one contact.
- I do advanced search for contacts with Activity = Today.
- Search gives me the one contact with Activity = Today.
- I create smart group out of that search.
- I go to Contacts > Manage groups and see that in my group is 1156 contacts (from which only one match criteria, namely, has Activity = Today).
UPDATE: Bug is replicated in CiviCRM Drupal Sandbox v4.7.14. http://dmaster.demo.civicrm.org/civicrm/group/search?force=1&context=smog&gid=7&qfKey=59a9c20b96f05a8c46befb01c385c298_1338
(Or see group Activity Today in Contacts > Manage Groups)