If I edit an activity (eg the date or the status) in the Activities tab of the Manage Case page, I get the confirmation message "[activity name] saved". But the edit is not saved.
This problem only appeared after upgrading to 4.7.4. There are no JS errors, no errors on CiviCRM log, no php errors.
Running Joomla 3.4.8. I can't test on the demo, because it's still on 4.6.
Edit: just tried the Wordpress demo, and the problem is present there as well.
Any suggestions where to look for the problem? Thanks.