EvilBlackSheep said:Moon said:That'll be going in just a second Sheep.

Thanks a lot. It re-scanned but the number didn't get fixed, still the same disparity, so I guess it'll have to stay this way :(
Thanks for trying though :)
I have a slight discrepancy as well. It is nothing on the scanners end in this case, and may just be a stray game that got wiped. For example, I played champions online for a while and got about 100 achievements, but something the devs did to the game seemed to reset everyone to a state of not having played it, so those achievements are acting as Schrodinger achievements: both there and not there.
tl;dr You may have games with achievements with no playtime on your account. Just my speculation.