Activity date filter ignored when viewing activity reports

Since upgrading to 4.7 we have observed the following problem:

Created a new Activity (contacts) report with

• the Activity Date filter set to This week
• the Navigation Menu Link To set to View Results

When running the report from the navigation menu the report is displayed without any filtering on Activity Date - the Activity Date filter has been reset to empty.

If I:

1. Set the (emptied) Activity Date filter to This week
2. Change the Navigation Menu Link To to Show Criteria
3. Click the Update Report button to save the changes
4. Re-run the report from the navigation menu

The report is not run, as expected, but the Activity Filter now remains set to This week. Clicking on the Preview Report button now produces the report I was expecting.

To see the problem on the demo site:
(4.7)http://dmaster.demo.civicrm.org/civicrm/report/instance/3?reset=1

Compare with 4.6 (while the Joomla demo site is still on 4.6):
(4.6)http://joomla.demo.civicrm.org/administrator/index.php?option=com_civicrm&task=civicrm/report/instance/3&reset=1