“Add New Post” page is completely blank

You seem to see the white screen of death. What this is and how you can find out the exact cause is described here in the article: https://developer.www.ads-software.com/advanced-administration/wordpress/common-errors/#the-white-screen-of-death

Thank you! It was the Gutenberg plug in. Really appreciate the help!

I’m glad you were able to solve it. You are welcome to set the topic to solved.