Im having the same issue where my insights are only showing a handful of games. Upgraded from platinum to diamond around 4 hours ago
It can take a while for games to all run, depending on how many you have. If you've previously had Diamond and Insight had been generated then, it can still take a while for the games played while you didn't have that level to complete. If you don't see anything after 24 hours, repost.
Im having the same issue where my insights are only showing a handful of games. Upgraded from platinum to diamond around 4 hours ago