Post Preview Links resulting in 404 page

Hello,

I’m having an issue with my post preview link. It worked before not when I click view post preview it show a 404 page.

For example if my post link is: https://www.onmakeupmagazine.com/postexample

and I try to preview it opens the page as: https://www.onmakeupmagazine.com/?p=1333

Which show a 404 page. Any help with this would be appreciated!

Thanks!