10 Days No Response

The two achievements that are glitched for me are Reign of Terror (Kill Diablo in Hardcore mode) 25G. & May His Death Satisfy You (Kill Malthael in Hardcore mode) 25G. I 100% as many games as I can. When something like this comes up where I am unable to obtain an achievement because of something out my control it bothers me. I have completed the said achievements in game and they show unlocked. The xbox achievements themselves are not showing up. I have tried multiple characters / seasonal / hardcore and everything in between. I can send screenshots of either my ingame achievements and or my xbox achievements showing as locked. Please help idk what to do. I have reached out to xbox support and blizz support and have been directed here.

my xbox GT is - xFrontLawnShawn