Due to some changes related to iOS, the new version of "iHome + Sleep" will not activate your alarm unless the app is running in the foreground and you have not manually locked the device. The developers are currently working to fix this issue. I assume developers of other alarm clock apps have also released new versions in which the developer(s) removed this feature. Therefore, I advise all users of alarm clock apps to refrain from updating their apps unless they are absolutely certain that the developer(s) has/have not removed this feature.