Preview does not reflect layout change on published posts

[XyZed]

Hello. I've been hoping this bug/oversight would be fixed for some years but it hasn't. When there is a post published in one particular layout format (e.g. three column, two columns or one column) and you decide to change the layout, you cannot preview your work unless you update the live version.

So in a nutshell, I have hundreds of articles I published in the three column format with ads down the right column. I needed to redesign each article to get rid of the right column. This requires a complete re-edit. But when I edit one of the three column posts and change the three column layout to the one column layout - I cannot preview my work. The "Preview Changes" button continues to display the post in three columns. In order to edit a page in the new one column format I have to "update" the page. This means you have to post a live version of a half edited page, which is very undesirable.

Andy

PS I work in the classic editor so don't know if it's same in block editor