I was getting a 404 Error with one of my CMS collections after a client published the site from the editor portal. I tried to change the collection URL as a work around and it gave me a “Could not find the details page for this collection”.
I was eventually able to to change the collection URL and then change it back to the original which fixed the problem.
Might be worth investigating.
Here is my site Read-Only: https://preview.webflow.com/preview/nofiltermuseum?utm_medium=preview_link&utm_source=designer&utm_content=nofiltermuseum&preview=24a610a9089a6beb18407ac7c145e701&pageId=5d850184478ff018e91a5069&itemId=5d850184478ff06afb1a5093&mode=preview
(how to share your site Read-Only link)