I have noticed that in Planet Press Design Tool 5.x that when you open a page's attributes window (by double-clicking the page in the Tree-View) and then check the Force-Front box and select a condition from the drop-down (or if you set these in the Object Inspector) that if you then reopen the page's attributes screen that the previously selected condition has been cleared from the box, and that if OK is clicked it will also be cleared from the Object Inspector and that the Force Front will no longer work. I had also noticed this happening in Planet Press 4.x.

I've noticed that this is fixed in the latest version 5 update!