When I add my Single Post Content element then my Single Post Hero disappears.
I have the element types set to Content Template for the Single Post Content and Page Hero for the Single post Hero.
I have turned off all other element locations and disabled all plugins.
Can you try changing the quick hook select to after header for the page hero element?
As the content template element kicks in, the default content area is gone, so the page hero can not find its position if it’s based on the content area.
The Quick Hook select is simply a shortcut to some of the many hooks available, those listed are just a few hooks that we think are most useful for that Element type.