Me and and a few other people (on a different forum) have also noticed this problem with itch.io right now. A number of pages have been showing 404 not found pages, sometimes up and sometimes not. My pages are still saved on my account, people just can't view it when it's published.
Yes. I've noticed it on and off. About 10 minutes after the first time it happened it was fixed. I only posted after it happened again half an hour after that. It has since started working, and stopped working twice for me. It is currently working now.