I achieved 950/1000 gamerscsore two weeks ago. And yet the Rewards Progress bar stopped at 120 gamerscore. Still only giving me 60/500 points on Forza 2, when i should have 475/500. Anyone else having this issue?
+1
I finished Forza Motorsports 3 but the last 2 achievements are not updating.
Also I have nearly finished Apex but only a few achievements show as completed
I haven’t checked to see if other rewards are updating.
Kind of frustrating 
Same here! FM2 completed as far as possible, 950/1000. Waiting for Tier update.
Seems that these days are being a mess for Turn 10 & Playground Games. I understand it.
I trust them. If they are able to build games as Motorsport and Horizon, they will fix a quite more simple problem with statistics files.
Just wait!
Came to forums to post the same thing. I am not that close to completion but I got a few achievements in it on the 8th. They list on the page as unlocked but don’t show towards the score.
At a guess FM2 may not get scanned for updates as often as there is a lot less likely to be people getting new achievements and new scores in it as there would be in say Forza 6.
That is assuming Forza Rewards takes players and scans for achievements periodically rather than when you go to the page.
EDIT: From the rewards FAQ,
For my FM2 achievements, tomorrow will be the 8th. But I think achievements are funky. According to the FR website I have not unlocked the complete a first lap in FM3 (or was it FM4) but I have got the achievement for hitting level 40.
Both Apex and Forza 3 are updating for me now
I logged in on the xboxone and got prompted to allow access
Accepted and checked 
Hope you guys are fixed as well
FM2 achievements just updated for me 