Hmm... have the same problem with some of the links.
And no backlink is needed/required in our case.
To me it seems like there is some problem with a cron job. Because we also have the "problem" that some links show up inside the "new link" on "whats new overview" and some don´t ... even several days later.
Just wanted to let you know.... Take your time. Wish you all the best!