Like many other developers, my FB app stopped working last week after Facebook blocked all apps using user_managed_groups permissions without review.
I have since submitted it for review. Has anyone been able to use user_managed_groups endpoint (groups/feed) after their app is approved?
Until further notice from Facebook, no one is able to access the Group API at the moment: https://developers.facebook.com/blog/post/2018/04/04/facebook-api-platform-product-changes
Testing of our more robust process starts today and the new process should resume in a few weeks, but apps currently accessing Events and Groups APIs will lose access today.
App Review is on pause. You can only wait until Facebook put it back on.