This bug existed in the original game. The spectre gear is super high level and so the vendor system of cycling stuff close to your level will cause the stock to be replaced with lower level items once you leave the area after it's loaded. It wouldn't come back until you hit level 50 and that level gear could spawn again.Fucking L O L
Mass Effect: Legendary Edition has a bug keeping players from obtaining the Spectre gear early on -- luckily there's a fix that can solve the issue.gamerant.com
This bug was never fixed in the original game, I doubt it'll get fixed here.