[Riven Mod lock "Find (x) Rare Medallions" is not counting any medallions.]

Lol, was just about to delete this post as I figured that out a few minutes ago. DE really needs to type this out somewhere.

[Riven Mod lock "Find (x) Rare Medallions" is not counting any medallions.]

I have a Rifle Riven Mod with the current lock: "Find 4 Rare Syndicate medallions"

At first I was told any medallion should increment the counter. However that didn't seem to be the case.

Then after 8 Syndicate missions I finally found a rare medallion, a General Insignia. However that didn't increment the counter.

I can't say if it doesn't work for other Rare Syndicate medallions, mostly because I can't be arsed to anymore of these excruciatingly long, RNG-fest rotten-egg hunts. 

 

Just had to equip the mod.