I played a few games during Starcraft 2 9th anniversary but I did not get the 9 Fine Years achievement for it.
I also have not gotten the Acheivement for buying a Starcraft 2 campaign before the 4.0 Patch called StarCraft II Veteran. Even though I have bought all my campaigns before that Patch and and played them before it.
I also played frequently before the anniversary.
Try with tech support on this forum, or open a ticket