Yeah, that happened to me too, a few times.
The blockchain was alright, though. This happens when the Steem Engine crashes (or its down) for some reason. Before you publish your post, check SteemPeak to see if the newest articles have the following two icons in the rewards:
If you only see the Steem Symbol and not the Steem Engine in most posts, it's better to wait for it to be fixed.
Later on, the articles appear in the Tribes frontends but until Steem Engine recovers your posts will be invisible in every Tribe. Meanwhile, it will only be visible on SteemIt, Busy, eSteem, SteemPeak and so on.
I see. I hope I remember that next time. Thanks.