Error in Soledad Theme

Hello, everyone,
I use the Soledad Theme and am very happy with it.
But now I have a k

First of all, the note that I use the Classic Editor plugin because I can’t get along with the Gutenberg.

Now to my problem:
When I create a page I can change the layout at the bottom…like if I want a sidebar and also select the sidebar.
When I create a post it doesn’t work. These options are missing here.
But if I deactivate the Classic Editor, it also works for posts.
Is there a known bug that prevents the posts in the Classic Editor from being set?

With the latest version of WordPress, widgets are based on Gutenberg, when you install the plugin to activate the Classic editor, you’re disabling the sidebars…

Hope it make sense.

yes exactly, the sidebars are deactivated. But strangely only for posts and not for the pages