Curl resulta em um 403 ao usar um proxy de squid

Question

Estou tentando acessar um endpoint com curl e um proxy HTTP do squid, no entanto estou encontrando erros 403 Proibidos quando tento fazer isso.

curl -X GET 'https://secure-store.nike.com/ap/services/catalogService?action=loadProduct&productId=12365263&catalog=7&view=short&lang_locale=en_GB&rt=json&country=SG'   -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8'   -H 'Accept-Encoding: gzip, deflate, br'   -H 'Accept-Language: en-US,en-SG;q=0.9,en;q=0.8'   -H 'Connection: keep-alive'   -H 'Host: secure-store.nike.com'   -H 'User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/69.0.3497.92 Safari/537.36' --compressed --http1.1 -vx http://proxyIP:proxyPort

A resposta é a seguinte: Essecomandodecurvaexatafuncionaparaforneceraseguinterespostaquandoeunãousoumproxy.

{"status" :"success","product" :{"id" :"12365263","displayName" :"Air Jordan 1 High Zip Men's Shoe","productName1" :"Air Jordan 1 High Zip","productName2" :"Men's Shoe","colorNumber" :"002","type" :"nikeProduct","styleNumber" :"AR4833","productSlug" :"air-jordan-1-high-zip-shoe-RLzHD7","colorDescription" :"Black/Dark Smoke Grey/Gum Light Brown/University Red","prdGroupId" :"12480023","nikeType" :"FOOTWEAR","description" :"Air Jordan 1 High Zip Men's Shoe","inStock" :true,"dynamicAttributes" :{"width" :"Regular","SalesChannel" :"Nike.com","sizeconversion" :"1162","publishdate" :"10/23/2018","sportPrimary" :"Lifestyle","hardlaunch" :"true","divisioncode" :"20","productType" :"1","simplecolor" :"2696","category" :"Shoes","modelType" :"1","brand" :"647","gender" :"Men","publishType" :"Flow"},"gender" :"Men","hexvalue" :null,"crossSells" :"false","catalog" :["2","4","7"]}}

Eu testei o proxy usando-o como um proxy do sistema, e os navegadores que eu uso conseguem acessar o terminal bem.

O que poderia estar causando isso?