I'll use Carlos' question and add my own in a new topic, as you suggested, Myr.
My observations relate to Northie's story Soul Music. I got a notification of the new chapter, and posting it has also placed the story high on the New Stories list on the main Stories page. But the chapter does not show in the Latest Story Updates on the right side of the main Forum and Stories pages, where it should say Northie Added chapter 14 to....
As far as I can work out, two other ongoing stories also appear on the New Stories list, without the new chapter making the Latest Story Updates list. Rough Justice and Stranger, but this is probably because both authors are still in the Moderation Queue procedure.
In contrast, Carlos adding a new CJ story has not made it appear in the New Stories list. However, it does show in the Latest Story Updates on the right side of the page (Carlos Added story Georgetown: Over The Rainbow). But there should also be a listing saying Carlos Added chapter 1 to..., just as with other new chapters posted. In addition, as Carlos pointed out, the story does not figure as the Latest story at the bottom of the Forum and Stories pages. And I did not get a Notification of Carlos posting, even though I follow him as author, and I normally get a notification when he posts a new story.
Of course there are plenty of other newly updated stories which appear on both list, so it's not a consistent bug. What did @Carlos Hazday and @northie do differently from the other authors? Carlos post-dates his chapters, but you said it wasn't that. Northie will have to tell whether the Soul Music chapter was posted in any special manner.
I hope this long-winded explanation will be useful.