Here's a post about the delay:
https://www.furaffinity.net/view/38252089/

It'll take around...12 weeks(?) for you to see my newest post when it's already out now...

Just saying, postybirb's queue for when these go out are weeks out, and I post artwork every 4 days.

1 picture per week (maybe) here
1 picture per 4 days

Do the math and you'll see, FA will be so far behind the post will literally be a year behind
Literally

There are so many other sites too choose from for the newest artwork though so that's really only an FA issue