This is an issue that has happened before. A completed blog in the queue to be published later disappears from view, and we have no way of knowing if its just there but invisible or if something has happened to it. I think you'll see I've raised this before.
Right now, Murals of LaCombe, Alberta is missing from our DrFumblefinger queue; both he and I saw it there last night, scheduled for 21 February.
so: A) Where is it? and B) Why does this happen and C) How do we avoid it?