Schedule content to automatically expire and change at a certain time, and notify people of expiration.
Yes. As of Version 2.0.0, Content Scheduler should actually work on WordPress Network Sites.
Check the plugin setting's "expiration period" and make sure you have waited at least that long before checking your content for expiration.
Make sure you have actually visited a page on your website after the post's expected expiration date. WordPress only fires off scheduled tasks when people actually visit the site.
Try simply deactivating the plugin and reactivating it, then testing again.
Other plugins that schedule events might handle scheduling incorrectly, thereby removing Content Scheduler's expiration period. Again, deactivating and reactivating Content Scheduler should re-instate the scheduling.