Sorry but that changes nothing!
Have a look at that Screenshot "PageLines Meta Setting" made while creating a new post:
You can choose "Show Tertiary Sidebar" although showing the Tertiary Sidebar is already setup in the Page Options Setup for BLOG Pages!
The Settings from the global Page Options Setup for BLOG Pages seems not to work...!?
I have the same problem on two more pages!
>> Just disabled all plugins but that changed nothing too.
>> If i put the Tertiary Sidebar into the sidebar wrap the same thing happens:
setting up global Page Options to "Show Tertiary Sidebar" but thats not working at all.
>>> Thats interesting: In Drag & Drop i unchecked the "hide by default" option
and i now can choose "Hide Tertiary Sidebar" in Pagelines Meta Settings below the post editor: