First issue - Google Maps doesn't work anymore through HTTP, only HTTPS. I tried:
acl googlemaps url_regex ^https://.*.google.com/maps/.*$
acl googlemaps url_regex ^http://.*.google.com/maps/.*$
but it doesn't help. Any ideas how to make it work?
In the squid.conf there is usually an ACL to automaticly pass "https" so your rule may not be processed.
Please confirm that the web browser is using the squid proxy.
Use a different http url.