I do a request to my Squid through CloudFront and receive a miss:

< content-type: text/html
< date: Thu, 17 Mar 2022 08:22:46 GMT
< server: Apache/2.4.48 (Ubuntu)
< cache-control: max-age=3153600000, public, only-if-cached, immutable
< last-modified: Thu, 01 Jan 1970 00:00:00 GMT
< x-cache-lookup: MISS from ip-172-31-68-17:3128
< via: 1.1 ip-172-31-68-17 (squid/4.13), 1.1 c929a0b0be95dbd556dd38270accc062.cloudfront.net (CloudFront)
< content-security-policy: default-src * 'unsafe-eval' 'unsafe-inline' 'unsafe-dynamic' data: blob: ws: wss:; img-src http: https: data: mediastream: 'unsafe-eval' 'unsafe-hashes' 'unsafe-inline' blob: ws: wss:; frame-ancestors 'self'; frame-ancestors https://allfilesnews.com https://*.allfilesnews.com
< x-frame-options: SAMEORIGIN
< link: <https://Reb1lBkV3d9kbe7qlaaC7nZDFGNEErQKHQBk51bdA6c.allfilesnews.com/Reb1lBkV3d9kbe7qlaaC7nZDFGNEErQKHQBk51bdA6c/VvaYNP0fJiVQfefYmC>; rel="canonical"
< expires: Thu, 15 Apr 2110 20:00:00 GMT
< vary: Origin
< x-cache: Miss from cloudfront
< x-amz-cf-pop: TLV50-C1
< x-amz-cf-id: t6P2Rr1HqwCmSDmzC4oVh2fzq25ooHzPY4OZPwWras-9tBbMqinr3Q==

You see that max-age is very long and Last-Modified is in deep past. Why then this (repeated, I already queried this URL no more than a few days ago) query to Squid gives a MISS?

Here is my Squid config:

read_timeout 60 minutes

http_port 3128 accel vhost allow-direct

cache_dir ufs /Files/main/cache 120000 16 256
cache_peer 127.0.0.1 parent 9003 0 no-query default
acl all src 0.0.0.0/0.0.0.0
http_access allow all
never_direct allow all
forward_max_tries 5

Note that 120GB of the cache space is nearly not used:

$ df -h /Files/main/
Filesystem      Size  Used Avail Use% Mounted on
Files/main      125G  187M  125G   1% /Files/main