When the warband reputation merge happened, there was a bug with a large portion of Dragonflight reps going missing from the rep menu.
They since patched this, and most show up as you would expect, however this was never fixed for Loam Niffen, which remains missing for me every login.
Thankfully it appears to be cosmetic only, as gaining any rep will make it appear and at the correct renown level, but its still annoying.
I havnt been able to check if this will make it not count against rep achievements.