Extra Credit Achievement for WP8 isnt unlocking

Ok so I had to get the Extra credit the hard way for xbox 360 since there is no real fix. I also have it for Xbox one and Windows 8 pc. Now I got a wp8 phone and got this game once again Extra credit achievement is not showing up I cant unlock any challenges because i complete them all and that buggie a-1 challenge with 50 grunts that reads for me 975/50 how do I resolve this issue.

Remove finally have every halo achievement forjust a few hours lol