It turns out that Microblog doesn't gather posts that contain extreneous tag somewhere around the beginning. I really miss the docs on this matter. When I include tag "#Kbin", my post doesn't appear in my magazine, but when I remove it, all is fine, post appears immediately.
What's the behavior here? I just checked and it seems that if I include extreaneous tag as the first one, post is ignored. When I move this tag after the featured one, the post appears on Microblog tab.
Oh, and by "extraneous tag" I still maintain the #kbin. When I try any other, it doesn't interfere and show the post as it's intended to. So, it looks like I cannot use #kbin hashtag as the first one specifically.