I installed Activity nightly on my test site that has the same problem, I joined some groups and went back to my profile, it just said "No activity to display.". I have all the latest nightly of CB, CB Autoaction, CB Activity and I use GJ RC1.
I do test everything on the frontend with both admin account and normal accounts, joining groups created by admin and normal user etc. All actions are published, I also check in system actions and they are also published. Autoaction is published, activity is published and groupjive is published.
I also checked in the backend on CB acitivty and "CB Activity: Activity" is empty. It is not firing any triggers when I join a group from the frontend with a normal user to a group that is created by a different user. I also deleted all my own actions to make sure they did not conflict with the system actions.
I will try a fresh install later today and installing all the latest directly, something must have messed up the triggers and it started with the GJ beta and did not end when migrating to RC1.
My testsite: GJ 2.7.0 -> GJ Beta -> GJ Rc1
Live site: GJ Beta -> GJ Rc1
The GJ 2.7.0 on my test site did fire on join group triggers. :side: