Hi,
I tried looking at all paizo blog posts with the Pathfinder Society tag.
While this displays some of the posts, it's missing quite a few too.
The first four are:
The England GM Team Marches on its Stomach
Gen Con 2015 News and Official Call for Volunteers!
Learning Exotic Spells
No Hablo Shoanti
The first four SHOULD be:
Faction Journal Cards
Represent Your Cause!
Shax's House of Pain!
The Plot Thickens
I don't think it's a problem of "New stuff doesn't show up" because some older stuff is missing too - Faction Evolution I and IV is missing from the "Show only PFS tags"-page but displays fine when showing the whole blog.
I'm unsure whether this extends to tags that are not PFS, didn't test this.