Medusa: You are not alone in experiencing this bug. Here’s a link to my post in case you’d like to read more about this issue: Comprehensive Thread Of All Top 500/Competitive Bugs. I put your thread under: Not Appearing On Leaderboards (Season 4). Please help in spreading the word about this megathread and other related threads regarding these issues.
Nano: That is true that there are far fewer players in competitive modes compared to non-competitive modes, but the relative percentage also varies greatly by region, platform, and even time of day, so I don’t think using using arbitrary percentages is all that useful. But getting back to the original post, I think OP is talking about a bug regarding a missing Top 500 leaderboard placement despite having met the requirements for it, which implies that a lack of players to form matches with is not their issue here.