Why does Report state browser caching not set when waterfall clearly shows it is?

[thompsonpaul]

I run a test which gives an F for browser caching and a long list of items with no expiry header.

But the waterfall clearly shows that on second load those files aren't' being redownloaded, and I know expiry headers are being applied in htaccess.

This happens on a number of sites - here's an example
https://www.webpagetest.org/result/18022...view_step1

Any idea what's up with this?

Paul