On my local install and UAT site, I'm getting Surrogate-Control/Surrogate-Key and X-Drupal-Cache-Tags, which is fine.
On production I only get X-Drupal-Cache-Tags (which shouldn't be there but I can deal with that) BUT no Surrogate-Control/Surrogate-Key which should be there.
As far as I can see the settings are all the same, so at the very least I should be getting the same but obviously not.
What could be preventing the Surrogate-Control/Surrogate-Key from appearing?
Closed: works as designed
3.14
Miscellaneous
Surrogate-Control and Surrogate-Key headers are stripped out from the user view when passing through Fastly. If you access your production site via Fastly does will not show. You can add a request header called Fastly-Debug:1 to your request which will surface them if you want to be sure.