Proxy parameter not used for Update-ACMECertificate

[XSBen]

When I use proxy all CmdLet work correctly except Update-ACMECertificate:

Update-ACMECertificate : Impossible de se connecter au serveur distant
Au caractère C:\scripts\Cert\Cert_Common.ps1:117 : 5
+     Update-ACMECertificate -VaultProfile cfb-vault $certGroup
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Update-ACMECertificate], WebException
    + FullyQualifiedErrorId : System.Net.WebException,ACMESharp.POSH.UpdateCertificate

In source: for Update-ACMECertificate CmdLet:

using (var web = new WebClient())
{
    if (v.Proxy != null)
        web.Proxy = v.Proxy.GetWebProxy();

    var uri = new Uri(new Uri(v.BaseUri), upLink.Uri);
    web.DownloadFile(uri, tmp);
}

For all other CmdLet:

using (var c = ClientHelper.GetClient(v, ri))
{
    c.Init();
    c.GetDirectory(true);

    var challenge = c.SubmitChallengeAnswer(authzState, ChallengeType, UseBaseUri);
    ii.Challenges[ChallengeType] = challenge;
}