I have been scratching my head over this for the last day or 2 and finally figured out what was happening. I thought I would post the solution in case any one else does a search for something similar.
When I clicked on a button (I'm using Unity) that had the code: Social.ShowAchievementsUI(); on it, there would be a pop up that displayed what should contain all the achievements, and just said "No data available. Further to that, after authenticating the user and displaying all the achievements I was getting errors trying to find the achievements in the xcode error log.
I was signed into a user not participating in the beta/test flight on iTunes Connect. As soon as I signed in with an invited user, I could see all of the achievements/badges.