Single sign on identityserver 4从所有客户端注销不起作用

我正在使用identity server Version=“4.0.0”我希望在客户端注销时从所有客户端执行注销。我正在尝试backoutchannel注销

例如：-我有以下连接到IS的应用程序URL。当客户端MVC1从URL注销时https://localhost:5002/ 其他客户端也应该注销。我浏览了他们说要添加backoutchannelURL的IS文档

https://localhost:5002/ （客户端：MVC1，BackChannelLogoutUri:https://localhost:5002/home/logout)

https://localhost:5003/ （客户端：MVC2，BackChannelLogoutUri:https://localhost:5003/home/logout)

https://localhost:5004/ （客户端：MVC3，BackChannelLogoutUri:https://localhost:5004/home/logout)

是-->accountController

    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Logout(LogoutInputModel model)
    {
        // build a model so the logged out page knows what to display
        var vm = await BuildLoggedOutViewModelAsync(model.LogoutId);

        if (User?.Identity.IsAuthenticated == true)
        {
            // delete local authentication cookie
            await HttpContext.SignOutAsync();

            // raise the logout event
            await _events.RaiseAsync(new UserLogoutSuccessEvent(User.GetSubjectId(), User.GetDisplayName()));
        }

        // check if we need to trigger sign-out at an upstream identity provider
        if (vm.TriggerExternalSignout)
        {
            // build a return URL so the upstream provider will redirect back
            // to us after the user has logged out. this allows us to then
            // complete our single sign-out processing.
            string url = Url.Action("Logout", new { logoutId = vm.LogoutId });

            // this triggers a redirect to the external provider for sign-out
            return SignOut(new AuthenticationProperties { RedirectUri = url }, vm.ExternalAuthenticationScheme);
        }

        return View("LoggedOut", vm);
    }

你知道为什么它不起作用吗

[HttpPost("Logout")]
    [AllowAnonymous]
    public IActionResult BackchannelLogout()
    {
        return SignOut("Cookies", "oidc");
    }