Nope, posting was fine, but I'd setup the cache wrong. Fixed that now (I think!) so all the dynamic pages are no-store, static pages with a query string (from asp-append-version) get a long (256 days) expiry, and static pages without a query string (which are mostly JavaScript modules loaded through other modules) get a must-revaliate.

I'm not happy about the growing number of headers, it's not doing wonders for the payload:content ratio. On the other hand, at least HTTP/2.0 means that there isn't a fresh connection for each file.