Right, I think I've seen at least one thread about this but without a solution for me.
I get "_wp_page_template" on every page, no matter if it is brand new or has had some changes in it. It occured for the first time when I started playing around with theme custumization. It hasn't got anything to do with plugins, and it doesn't help deleting any hidden stuff under "advanced" as it just pops up again.
Someone thought it was some meta-stuff, but I haven't got a clue what to look for.
Help, links, suggestions are very much appreciated. Thanks!