Hi Everyone,
I thought I would let others know if you are having issues with your site and s2Member please check to make sure you do not have WP-Optimize by UpdraftPlus installed.
I was having some issues with a few things that made s2Member not work. I found that WP-Optimize to be the root cause. Even with it not active it still effected the server, the plugin had to be deleted before the system would worked again.
As of June 2017, I suggest staying away from this plugin and possible plugins by this developer on member sites, it is not worth the headaches. I only hope to help others from frustration, I am sure the plugin works great for other sites but I can only say it was a really bad plugin for me as it effected multiple plugins I depend on, not just s2Member.
Ross