freespirit wrote: »Found it!!
It is indeed an addon, it's a setting in Loot Log addon, I had no idea it was there and I had it turned on! Ooops!!
@Psyonico, in the antiquities panel, if you select the antiquity and then press E to view the actual codex, you will see the individual messages from all parts, then you can see which ones you have completed (the ones with the filled diamond at the left), as seen in this picture: