Hi.
I just tried (in 2018.1 x64) to add a Separator to the Page Content list. When I tried to move the Separator to the top of the page content list, both my previous Header and List items lost their settings.
I also tried to put the Header and List to the bottom instead, but that resulted in much the same rresult.
It looks like the settings aren't following the rearranged items.
This looks very much like a bug to me.
Cheers.