Pages and events disappear on multisite

I have 14 multisites and am using Multisite Content Copier to share posts with them from the main site. It's been working great, except suddenly some of the locally added pages and events have just disappeared from the local sites. This has happened on two of my sites so far. The local admins have had to add the pages and events back. Weirdly, the posts that were added to their sites with Content Copier did not disappear. Any idea why the local content would suddenly disappear from the site and the local admin?