Stuff not showing up in home page?

I noticed today that a post made in my Mental Illness group didn't show up in the home page and checking the timestamps I confirmed that it wasn't there. However (just now) going to check that I hadn't mistaken AM for Pm or vice versa it is where it was meant to be, so does imzy have a filtering system I hadn't realized, and maybe it only just hit that threshhold to be shown on my home page? Or is this a bug?
I was also able to take a few screenshots which I will link to as I still can't learn how to embed for the life of me cough cough please somebody explain cough cough

here you can see the timestamp of the post
here you can see where it should have gone (between the two posts)
and finally here you can see the post magically appearing between the two