Silent access does not provide valid token

I installed the sample and everything works fine. I wanted to use the token from the "silent"-authentication sample in a graph call, so I copied the ajax call from the simple.hbs into silent.hbs and called it after token validation.
This is my code in silent.hbs:
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<html>

<head>
    <title>Silent Authentication Sample</title>
</head>

<body>
    <p>
        This sample demonstrates silent authentication in a Microsoft Teams tab.
    </p>
    <p>
        The tab will try to get an id token for the user silently, validate the token and show the profile information decoded from
        the token. The "Login" button will appear only if silent authentication failed.
    </p>

    <!-- Login button -->
    <button id="btnLogin" onclick="login()" style="display: none">Login to Azure AD</button>

    <!-- Result -->
    <p>
        <div id="divError" style="display: none"></div>
        <div id="divProfile" style="display: none">
            <div>
                <b>Name:</b>
                <span id="profileDisplayName" />
            </div>
            <div>
                <b>UPN:</b>
                <span id="profileUpn" />
            </div>
            <div>
                <b>Object id:</b>
                <span id="profileObjectId" />
            </div>
        </div>
    </p>

    <script src="https://code.jquery.com/jquery-3.1.1.js" integrity="sha384-VC7EHu0lDzZyFfmjTPJq+DFyIn8TUGAJbEtpXquazFVr00Q/OOx//RjiZ9yU9+9m"
        crossorigin="anonymous"></script>
    <script src="https://statics.teams.microsoft.com/sdk/v1.0/js/MicrosoftTeams.min.js" integrity="sha384-SNENyRfvDvybst1u0LawETYF6L5yMx5Ya1dIqWoG4UDTZ/5UAMB15h37ktdBbyFh"
        crossorigin="anonymous"></script>

    <!-- Check before upgrading your ADAL version, as this sample depends on an internal function to authenticate silently -->
    <script src="https://secure.aadcdn.microsoftonline-p.com/lib/1.0.15/js/adal.min.js" integrity="sha384-lIk8T3uMxKqXQVVfFbiw0K/Nq+kt1P3NtGt/pNexiDby2rKU6xnDY8p16gIwKqgI"
        crossorigin="anonymous"></script>

    <script type="text/javascript">
        microsoftTeams.initialize();

        let upn = undefined;
        microsoftTeams.getContext(function (context) {
            upn = context.upn;
            loadData(upn);
        });

        // Loads data for the given user
        function loadData(upn) {
            // ADAL.js configuration
            let config = {
                clientId: "{{appId}}",
                redirectUri: window.location.origin + "/tab-auth/silent-end",       // This should be in the list of redirect uris for the AAD app
                cacheLocation: "localStorage",
                navigateToLoginRequestUrl: false,
            };

            // Setup extra query parameters for ADAL
            // - openid and profile scope adds profile information to the id_token
            // - login_hint provides the expected user name
            if (upn) {
                config.extraQueryParameters = "scope=openid+profile&login_hint=" + encodeURIComponent(upn);
            } else {
                config.extraQueryParameters = "scope=openid+profile";
            }

            let authContext = new AuthenticationContext(config);

            // See if there's a cached user and it matches the expected user
            let user = authContext.getCachedUser();
            if (user) {
                if (user.userName !== upn) {
                    // User doesn't match, clear the cache
                    authContext.clearCache();
                }
            }

            // Get the id token (which is the access token for resource = clientId)
            let token = authContext.getCachedToken(config.clientId);
            if (token) {
                showProfileInformation(token);
            } else {
                // No token, or token is expired
                authContext._renewIdToken(function (err, idToken) {
                    if (err) {
                        console.log("Renewal failed: " + err);

                        // Failed to get the token silently; show the login button
                        $("#btnLogin").css({ display: "" });

                        // You could attempt to launch the login popup here, but in browsers this could be blocked by
                        // a popup blocker, in which case the login attempt will fail with the reason FailedToOpenWindow.
                    } else {
                        showProfileInformation(idToken);
                    }
                });
            }
        }

        // Login to Azure AD
        function login() {
            $("#divError").text("").css({ display: "none" });
            $("#divProfile").css({ display: "none" });

            microsoftTeams.authentication.authenticate({
                url: window.location.origin + "/tab-auth/silent-start",
                width: 600,
                height: 535,
                successCallback: function (result) {
                    // AuthenticationContext is a singleton
                    let authContext = new AuthenticationContext();
                    let idToken = authContext.getCachedToken(config.clientId);
                    if (idToken) {
                        showProfileInformation(idToken);
                    } else {
                        console.error("Error getting cached id token. This should never happen.");
                        // At this point we have to get the user involved, so show the login button
                        $("#btnLogin").css({ display: "" });
                    };
                },
                failureCallback: function (reason) {
                    console.log("Login failed: " + reason);
                    if (reason === "CancelledByUser" || reason === "FailedToOpenWindow") {
                        console.log("Login was blocked by popup blocker or canceled by user.");
                    }
                    // At this point we have to get the user involved, so show the login button
                    $("#btnLogin").css({ display: "" });

                    $("#divError").text(reason).css({ display: "" });
                    $("#divProfile").css({ display: "none" });
                }
            });
        }

        // Get the user's profile information from Microsoft Graph
        function getUserProfile(accessToken) {
            $.ajax({
                url: "https://graph.microsoft.com/v1.0/me/",
                beforeSend: function (request) {
                    request.setRequestHeader("Authorization", "Bearer " + accessToken);
                },
                success: function (profile) {
                    $("#profileDisplayName").text(profile.displayName);
                    $("#profileJobTitle").text(profile.jobTitle);
                    $("#profileMail").text(profile.mail);
                    $("#profileUpn").text(profile.userPrincipalName);
                    $("#profileObjectId").text(profile.id);
                    $("#divProfile").css({ display: "" });
                    $("#divError").css({ display: "none" });
                },
                error: function (xhr, textStatus, errorThrown) {
                    console.log("textStatus: " + textStatus + ", errorThrown:" + errorThrown);
                    $("#divError").text(errorThrown).css({ display: "" });
                    $("#divProfile").css({ display: "none" });
                },
            });
        }

        // Get the user's profile information from the id token
        function showProfileInformation(idToken) {
            $.ajax({
                url: window.location.origin + "/api/validateToken",
                beforeSend: function (request) {
                    request.setRequestHeader("Authorization", "Bearer " + idToken);
                },
                success: function (token) {
                    $("#profileDisplayName").text(token.name);
                    $("#profileUpn").text(token.upn);
                    $("#profileObjectId").text(token.oid);
                    $("#divProfile").css({ display: "" });
                    $("#divError").css({ display: "none" });
                    getUserProfile(idToken);
                },
                error: function (xhr, textStatus, errorThrown) {
                    console.log("textStatus: " + textStatus + ", errorThrown:" + errorThrown);
                    $("#divError").text(errorThrown).css({ display: "" });
                    $("#divProfile").css({ display: "none" });
                },
            });
        }
    </script>
</body>

</html>
As you can see, I only copied and pasted the code in line 168-190 and called it in 205.
This is the result:
Some tests have shown, that the token in local storage remains the same, even after logging in and out of Teams or deleting all browser history and caches.
Any ideas, what to do to resolve this issue? As we can only submit our app with working silent authentication and we can't get it working we are quite helpless.
OfficeDev / microsoft-teams-sample-complete-node

Silent access does not provide valid token #45
