Make sure to log into each of your characters. Only will the story missions and other achievements be "pushed" if you log into that character.
Make sure that you have all the datacrons for an achievement on one character. The achievement does not track the datacrons across characters. Also, make sure to log in on that character.
Ofc i logged on all characters, relogged multiple times - didn't work
About datacrons - you can't have all datacrons on one character, as Imp version (Balmorra, Taris) is existing.
So now i'm missing imp datacrons -> so no achievement