Maintenance for the week of July 13:
• PC/Mac: No maintenance – July 13
The issues on the North American and European PlayStation® megaservers have been resolved at this time. If you continue to experience difficulties at login, please restart your client. Thank you for your patience!
You also can't have the stream muted, or that time doesn't count.
EDIT: You can mute the tab, or mute the application in your system settings, but if the stream player itself is muted, it doesn't count for drops. It also doesn't count if the stream isn't in an active tab. (You can have a different browser up and running, but you can't tab away to something else and get the drop timer to progress.)