How much Rank confidence do you need for Immortal Rank Medal?

[Adal]

I got to 7k MMR, played much more than 14 games in the last 21 days but still got no Rank medal. I looked on Reddit and some said that i need at least 40% Rank confidence, but i still haven't gotten my medal yet, even though i also have more than 40% Rank confidence

[Nox Eterna]

70%