OK, now I remember. I actually saw this appear on a timeline I was working on for groups; that is why I thought it was my coding error. For some reason, in the group timeline it wouldn't show the post after the "Today" divider. When I went into the inspector; I saw where the post was there, but it was being hidden. So I went looking in the js code for the script that added the hidden parameter.
In my case I changed the code to the following; note that gwall is group wall. We were discussing this one day if you recall. Since it was hiding it I just change it to show(). Hopefully you can look at it and figure out if this is some Boonex coding error.
$('.gwall-view .gwall-events div.gwall-divider-today').after($(sResult).show()).next('.gwall-event:hidden').agwallanim('show', $this._sAnimationEffect, $this._iAnimationSpeed, function() {
$(this).find('a.bx-link').dolEmbedly();