Maybe I don't get something, but addon only shows me Naxx 10, and not 25. Ulduar is missing whatsoever. Looks like it checks if I have an achie for that tier, and ignores it if I do, even tho I got it on other char and don't have that set on this char. Is it even a bug, or intended?

Are you referring to the actual tier sets in the Item Sets area?

If so that's because not all of the tier sets have been added so far.

Item Sets > Tier Sets, yeah.Do you need help adding them or something?

The tier sets just take a bit more time pulling information from Blizzard. Since we used the localized headers from Blizzard. Then it's a matter of pulling all the pieces that go with each set. The API gives some extra pieces and stuff. Plus splitting the sets apart into different specs.

I've also been strapped for time with school and haven't put much focus on it and been working on other areas as well.