Concerning the topic starter's problem, this is also related: Geo-Coordinates - Behind Corporate Proxy
It seems that the IP address where the map is hosted, is listed by firehol as a threat, often used as input for ip blacklists: https://raw.githubusercontent.com/firehol/blocklist-ipsets/master/firehol_level1.netset
In my case, catalogue.maps.elastic.co translates to 216.239.38.21, one that's present in the blacklist.