PowerShell Get-PackageProvider拒绝使用代理问题求助

我已查阅过该问题的相关帖子，这类问题通常与代理设置和/或TLS1.2配置有关。我已完成这两项配置，并尝试了各种方式设置代理，但流量仍走直连（DIRECT）。

当前WinHTTP代理设置 #

PS C:\Windows\system32> netsh winhttp show proxy
Current WinHTTP proxy settings:

    Proxy Server(s) :  proxy.here.com:1234
    Bypass List     :  (none) 

脚本及执行输出 #

脚本内容 #

$proxy = 'http://proxy.here.com:1234'
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
[system.net.webrequest]::defaultwebproxy = new-object system.net.webproxy($proxy)
[system.net.webrequest]::defaultwebproxy.credentials = [System.Net.CredentialCache]::DefaultNetworkCredentials
[system.net.webrequest]::defaultwebproxy.BypassProxyOnLocal = $true
$env:http_proxy = "http://proxy.here.com:1234"
$env:https_proxy = "http://proxy.here.com:1234"

Get-PackageProvider -Name NuGet -ErrorAction 'SilentlyContinue' -Force -Verbose

执行输出 #

VERBOSE: No match was found for the specified search criteria and provider name 'NuGet'. Try 'Get-PackageProvider -ListAvailable' to see if the provider exists
 on the system.
VERBOSE: Finding the package 'Bootstrap::FindPackage' 'NuGet','','0.0.0.1','''.
WARNING: MSG:UnableToDownload «https://go.microsoft.com/fwlink/?LinkID=627338&clcid=0x409» «»
VERBOSE: Cannot download link 'https://go.microsoft.com/fwlink/?LinkID=627338&clcid=0x409', retrying for '2' more times.
WARNING: Unable to download from URI 'https://go.microsoft.com/fwlink/?LinkID=627338&clcid=0x409' to ''
VERBOSE: Cannot download link 'https://go.microsoft.com/fwlink/?LinkID=627338&clcid=0x409', retrying for '2' more times.
VERBOSE: Cannot download link 'https://go.microsoft.com/fwlink/?LinkID=627338&clcid=0x409', retrying for '1' more times.
VERBOSE: Cannot download link 'https://go.microsoft.com/fwlink/?LinkID=627338&clcid=0x409', retrying for '1' more times.
VERBOSE: Cannot download link 'https://go.microsoft.com/fwlink/?LinkID=627338&clcid=0x409', retrying for '0' more times.
WARNING: Unable to download the list of available providers. Check your internet connection.
VERBOSE: Cannot download link 'https://go.microsoft.com/fwlink/?LinkID=627338&clcid=0x409', retrying for '0' more times.

流量异常情况 #

我监控了主机的所有出站流量，未发现访问上述URL的请求，反而看到一系列对https://onegetcdn.azureedge.net/providers/providers.masterList.feed.swidtag的调用——这些请求完全不走代理，直接直连并被防火墙拦截。我尝试了各种方法都无法强制该流量走代理。

更反常的是，在同一个PowerShell会话中，用Invoke-WebRequest访问这个URL却能正常通过代理：

PS C:\Windows\system32> Invoke-WebRequest -Verbose https://onegetcdn.azureedge.net/providers/providers.masterList.feed.swidtag
VERBOSE: GET https://onegetcdn.azureedge.net/providers/providers.masterList.feed.swidtag with 0-byte payload
VERBOSE: received 1847-byte response of content type text/plain; charset=utf-8

StatusCode        : 200
StatusDescription : OK
Content           : <?xml version="1.0" encoding="utf-8"?>

内容的提问来源于stack exchange，提问作者klaypigeon