i was having the same problem. after updating, my home page kept saying not found, even if i could edit it just fine. it fixed itself after like an hour or two without me doing anything. idk why it's happening, but it's definitely not just you
was experiencing this not too long ago as well. neocities has just been funky lately!
i had this same issue on one section of my site - i noticed if i have a folder with the same name as a page (So, a "Features" folder and then a page that was .com/Features) it gave me the not found error. I changed the page name and it resolved.
omg, i love this so much wow! it's super fun moving the photos around to get a better look, just like you would rifling through a stack of old photos at the table :)
Awesome!