Can’t edit posts/pages featured image

Dear support,

I am using WordPress 5.8.1, but I can’t set featured images for posts, pages and custom post. I’ve tried to desactivate all the plugins I use but there is no changes, the option is still not visible.

I made searches on Internet and many people suggest to turn the “Featured image” tab visible from the “Screen Options” tab, but when I edit a page, an article or a custom post, I can’t see the tab “Screen Options” on the top right of the screen.

Any idea ?

Thanks in advance !

Chris