I think the subject line reflects what is happening. I had a forum post with the following subject line:
Race on to save Egypt's ancient treasures
I tried moving this post from the forum it was originally in to another forum. It said the post was moved. In fact, the bread crumb trail showed the new forum even above the original post. But then when I went to the main forum pages, it was still in its original forum. I tried this several times, and it remained where it had been originally. Noticing there was an apostrophe in the subject line, I took a wild stab at it and reworded the subject line without the apostrophe. I was then able to move the post.