Can't save page in Cornerstone after clicking "Edit with WordPress"

I have one specific page that will no longer save in Cornerstone after I clicked “Edit with WordPress” on the normal WordPress editor page:

Now on the WordPress editor page, I can’t see the normal “Edit with Cornerstone” option, instead it just shows shortcodes in the blocks editor.
shortcodes

I am seeing this error when I try to save the page now in Cornerstone:
saveerror

No other pages are having this issue and this page only started having this issue after I clicked “Edit with WordPress”.

I tried deactivating plugins but that did not fix. What is causing this and how can I fix it?

I sent login information in a secure note.

Thank you!