Where is a hidden post to Facebook group located for its Admin? ie ., if Admin hides a post a message is received that the contents of the post are available. Where can I find them?
This may helpful.
How do I add friends, Pages, groups, events or apps back to my news feed after I hide them?
From your home page:
1- Hover over the News Feed bookmark in the left column, Click the icon that appears to the left and select Edit Settings.
2- Scroll to the Apps section and click the X next to the name of the app whose stories you want to unhide
3- Click Save
Removing someone or something from your list of hidden stories means those stories can appear in your news feed again.
Source: Facebook Help Center
Have a look: https://www.facebook.com/help/418065968237061/