Upon checking your page I could not figure out why this specific page is facing the issue while the other and the new pages do work.
To help you solve the issue here is what I did.
I went to your page and as the preview did not work I selected Skeleton mode view.
On Cornerstone > Templates > Save as a page template
Create a new page and added page template and saved.
I renamed your page How it Works to How it works Old and saved as a draft
the new page is called How it works as before also the slug.
Everything seems to be good
Let us know if you notice any strange behaviour on other pages.