Interestingly, I am not having this problem on a media temple grid server site, but I am having it on a Liquidweb VPS; both running PHP 5.6.21. I opened a ticket with Liquidweb and they are not actually seeing an error messages at the server level. They reviewed cUrl/libcurl settings and capabilities and all are there – it should not have trouble deflating. There is no security feature blocking the download either.