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 5). Please help in spreading the word about this megathread and other related threads regarding these issues.
Here’s a recent thread about your missing Top 500 leaderboard placement issue if you’d like to read more about other potential solutions: Comprehensive Thread Of All Top 500/Competitive Bugs - #318 by Azdyph-1127.