I think I found the problem. When a page is created by "Create New - From Plug-in", the created page is not recognized in the system. Hence, that page can't be used as a destination. The bug is deeply hidden since that page can be seen in the drop-down, and can be selected. It is just the ...
Maybe I am stupid, but I can't find the button to duplicate an existing screen. Please point me to the right direction, and a screenshot would be wonderful.