Thanks @dax1,
I did notice a post disappear this morning at 9:30 BST (British summertime). But it was rather an unusual case. The Post was in the installation and trouble shooting section, and one member had pointed out it was in the wrong section. The OP then posted to say sorry.
I was about to move it elsewhere when the screen flashed and the original post had gone, leaving only the member and the OP's reply left. So I did not move it myself.
I don't know if this was another member moving it of the spam filter kicking in as I watched.
It is entirely likely that this was before your fix, but thank for that change of behaviour that should make things more clear in future.