Why does Cloudflare "REVALIDATED" when I have set max-age and s-max-age in Cache-Control? Seemingly ignores s-max-age? [SOLUTION]

I’ve just solved this problem, but it took me a few hours, so I figured I’d make a post that will hopefully be in the Google search results for the next person that has this problem:

The correct header value is s-maxage, NOT s-max-age. So a Cache-Control header that never caches at the client (browser), but stores the file in Cloudflare for 1000 seconds would be:

Cache-Control: public, max-age=0, s-maxage=1000

Once I corrected the header, Cloudflare stared HITing like it should.

I have no idea why max-age has the hyphen between “max” and “age”, but s-maxage doesn’t ¯\_(ツ)_/¯