Our corporate firewall/proxy is keeping VS Code from being able to install extensions because Code doesn\'t trust something in the chain. It doesn\'t reliably give an error,
This is a terrible answer (not very secure), but appears to be the current Microsoft official answer. Use "http.proxyStrictSSL": false in your settings.json file.
This should work to get around the issue of installing extensions inside a corporate network, but I'd recommend disabling the setting if you are going to be working from home/coffee shop and not connected to the corporate VPN.
https://github.com/Microsoft/vscode/issues/3492