Facebook graph API for Group Feed shows permission not sufficient

I have been trying to access a Group's Feed through graph api. I am the admin of the group and trying to access in graph api explorer. Here is the error message it returns

{
  "error": {
    "message": "(#100) Insufficient permission",
    "type": "OAuthException",
    "code": 100,
    "fbtrace_id": "xxxxxxxxx"
  }
}

I double checked the permission list. I have included publish_to_groups, groups_access_member_info, groups_show_list, user_managed_groups

But it is strange that it still throws that error. Has anything changed recently ? Is there any permission I forgot to add ?