Cant change page hirarchy

I cant change the hirarchy of my pages anymore. The pages are children of “Home” and should be children of another page. When I try to change the parent and save, it just switches back. I even tried to erase home. Then the pages are assigned to “main”. If I recreate “home”, they are children of “home” again.-

Maybe this is because of the WMPL Mulilanguage plugin, but I cant deactivate it, because people are currently working on the translations.