Not to want to raise an argument here, but if it isnt a bug why they should say anything? its up to you, or us to find the lore :P they dont need to tell you where it is.
What is buging me is i got all datacrons on taris and the codex is still 4/5... and im positivly certain i got all 5.
That's interesting. I will prob unlocked this codex on another planet. It happened on Tython with the Wingmaw entry.