The feature, which suppresses calls and other notifications when activated, began acting up for some users on January 1.
Do Not Disturb schedules stopped expiring as some iPhone users had requested as 2013 commenced on Tuesday morning, meaning calls and notifications were still being diverted.
In a post on its support pages, Apple said it was working on a fix and advised users to switch the feature on and off manually in the meantime.
Switch Scheduled Off
The post read: "Do Not Disturb scheduling feature will resume normal functionality after January 7, 2013. Before this date, you should manually turn the Do Not Disturb feature on or off.
"To turn off the scheduling feature, tap Settings > Notifications > Do Not Disturb and switch Scheduled to Off."
The Do Not Disturb feature is handy when you're on holiday, or simply trying to get a good nights rest as it can be configured to only ring when your favourite contacts call.