Just joined Live half my Gamerscore missing

Had my 360 since 2006 but I'd never taken it online. Finally set it up today and half of my games didn't have their achievements added. Most noticeably Dead Rising where I had several. When I looked at my gamerscore on live it was listed at 1325 but when
I'd check offline or compare with friends it'd be around ~2500. Was advised to delete the live profile and redownload it, which I did, and made very careful to delete only the profile, but when I downloaded it again it outright removed those achievements from
the system and not just my profile. Can anything be done to get these back?

:)

 

Gamerscore glitched up?

Sometimes, achievements take up to a couple hours to update on xbox.com. It's rare to see them update right away. If it's just those 15 gamerscore, then that's nothing to worry about. Is it legitimately half (or a good chunk) of your gamerscore missing?

 

gamerscore issues

Ive noticed that some of my gamerscore is not adding up with the achievements Ive earned, this happened when i joined xbox live in 2009, I was playing without live for 4 years before i joined. Once i joined it showed the achievements ive earned but didnt
show the correct gamerscore. since then Ive not been able to re do those particular achievements as it shows ive earned them but hasnt given me the gamerscore for them. can anyone help me please as ive worked realy hard for those achievements and have lost
them.

 

If you're gamertag was never set up for Live (ie. you had to add an email to it) then those achievements may never populate on that account.

If you've just had the console offline but with a Live enabled account then there is a chance that those achievements may pop in time but it will take a while for them to do so.