Hi, I have the same problem, I added a new sidebar, saved, but the post or page I do not have the option to select it, why?
Admin user > Appearance> Custom Sidebars > New Sidebar > «New» (name ex.) «description» sidebar about > «create Sidebar» I see it in «All the Custom Sidebars»
But when you are editing the page in the «about» «page: right sidebar»…. the «Sidbars» is empty….
Tnx
e.