Referred Link - https://social.technet.microsoft.com/Forums/en-US/ca122d0f-e3f6-4ee0-b003-8e7f2bddb977/new-sharepoint-2010-user-group-not-showing-up-after-created?forum=sharepointadminprevious
Applicable on - SharePoint Editions 2010/ 2013
Recently we have a created a user group in SharePoint 2013 site and after adding, It is not visible in Site Settings - Site permission.
The root cause is Site Permissions link will display the groups which has permission level. So add a permission level.
To add Permission level
- Goto User Group
- List Settings
- Permission for the list
- Grant Permission
Tip to identify
Cross verify the group is visible under Site Settings - People and Groups - More