Leaderboards not showing
In a world using all player-persistent variables and all leaderboards, the leaderboards function properly in build and preview mode but do not load data in the published instance.
Secondary to this, multiple people have reported that "the first visitor to a published world cannot see the leaderboard data."

Thanks for this report! This has been identified by the team and we’re working to fix it.
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Laex05 commented
*The most important part of this is that the first person into a world does not see the leaderboard. This happens to me all the time and I have to go to my personal space and come back.
ie.
Published World, Launch Open Session, Can't See Data (sometimes 1-2 of the 3 leaderboards will load), run to personal space and come back, voila. :)