I currently have a Cloudflare Pages site, served with a custom domain, and I have enabled HTML caching for a subfolder (using Cache Everything page rule). It seems to be working, in the sense that the responses all have CF-Cache-Status: HIT, but the responses have no ETag or Last Modified headers. If I request the same pages directly from the Cloudflare Pages URL (https://whatever.pages.dev/index.html) the tags are there, but not via https://www.mysite.com/index.html.
Is there some setting that can conflict with the ‘Cache Everything’ page rule causing it not to include these headers? They’re present on all other cached resources (images, json etc), but not .html files.