2 days ago I did made a post in in a online campaign thread, it was just after this post.
It was a perception check, the whole text was:
Perception: 1d20 + 6 ⇒ (9) + 6 = 15
and the result was a 22.
I clearly saw the result of the die roll, and even saw the post a few hours later, now it has disappeared.
As I was able to see it after a few hours I hadn't simply made a preview of the result and forgot to submit it. I had no reason to add further text to the check so there was no motive to made a preview before submitting the result.
I am not completely sure, but I am under the impression that a couple of post by other poster I had read in the forum have disappeared too.
If it can be relevant, I am using Firefox 47.0.1 and when I closed the browser after making that post (and a lot of other stuff) the browser closed improperly.