If no one in your server has ever used your bot (inside or outside of your server), then there will be no one on the leaderboard. Consequently, there will be no leaderboard.
If none of the commands are working, something's probably gone wrong with the bot. If only a few commands aren't working, Luka may be missing permissions. Music commands are finnicky, and they don't always work. They're an alpha feature, and we don't recommend using them. Some commands, like the -reddit command, require updates and maintenance. That takes time, so these commands may be offline for an extended period of time. The bot should still work fine.
We may be working on Luka, or our hosting service may have gone dark. We'll always do our best to get Luka back up as fast as possible, but Luka is not our full-time job.
Honestly, no. Luka Premium isn't much of a service as it is a donation with some small perks. For all the "we"s I use on the site and in the bot, I'm a solo developer who has to go to school, pay for hosting, and still develop the bot. You may have noticed that Luka asks for Nitro. This isn't, in truth, for security. It's because alone, I don't have any idea whatsoever on how to implement secure payment systems. So if you feel like making my day with a purchase, go ahead. But please don't waste your money just to unlock some commands and a server. Please.