On Evoq Engage, Group Spaces are used along with the other social modules such as Answers, Ideas, Blogs, etc. The default group implementation is to add the Group Spaces module to every page with a social module and have all these pages at the same level. This type of implementation is called Single Level where all group pages are on the same page level.
Additionally, there is another type called 'Two Level' which is basically having a parent page with the group spaces module, and then having children pages for the social module +group space module. For this type of implementation, all group space modules should be set to Two Level.
Having a different setting than the way the page order is implemented will result on some of the social pages not being listed/available for the Group.
Make sure the right Group Space setting is being used (Single Level / Two Level), based on your implementation.