Have you tried to see if it tracks downloads of files accessed via the S2Member AWS S3 protected links mode or are you just tracking downloads of files stored on the file system of your server?
That's why S2Member Secure File Browser was my go-to plug-in. It was the only one that tracked those.
FYI - I will be forking and updating the S2Member Secure File Browser in 2 months. I will update here once there is an upissue available.