Issue logging out non-SAML authenticated user when sustainsys OWIN middleware enabled

Using sustainsys I am trying to setup SAML authentication as well as a backdoor for standard username/password authentication via in app form.

I can log in and out via SAML without any issue.

I can log in via the in app form but when it comes to logging out, while it does log out successfully I get an exception:

[SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)]
   System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, DbConnectionPool pool, String accessToken, Boolean applyTransientFaultHandling, SqlAuthenticationProviderManager sqlAuthProviderManager) +1081
   System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions) +463
   System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection(DbConnection owningConnection, DbConnectionPoolGroup poolGroup, DbConnectionOptions userOptions) +38
   System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection) +846
   System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +143
   System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +17
   System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry) +139
   System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry) +448
   System.Data.SqlClient.SqlConnection.Open() +129
   System.Web.Management.SqlServices.GetSqlConnection(String server, String user, String password, Boolean trusted, String connectionString) +75

[HttpException (0x80004005): Unable to connect to SQL Server database.]
   System.Web.Management.SqlServices.GetSqlConnection(String server, String user, String password, Boolean trusted, String connectionString) +130
   System.Web.Management.SqlServices.SetupApplicationServices(String server, String user, String password, Boolean trusted, String connectionString, String database, String dbFileName, SqlFeatures features, Boolean install) +92
   System.Web.Management.SqlServices.Install(String database, String dbFileName, String connectionString) +28
   System.Web.DataAccess.SqlConnectionHelper.CreateMdfFile(String fullFileName, String dataDir, String connectionString) +365

The logoff controller looks like:

public ActionResult LogOff()
{
    AuthenticationManager.SignOut();
    return RedirectToAction("Login", "Account");
}

And the middleware is setup like this:

        app.CreatePerOwinContext(SystemContext.Create);
        app.CreatePerOwinContext<ApplicationUserManager>(ApplicationUserManager.Create);
        app.CreatePerOwinContext<ApplicationSignInManager>(ApplicationSignInManager.Create);

        app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);

        app.UseCookieAuthentication(new CookieAuthenticationOptions
        {
            AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
            LoginPath = new PathString("/account/samllogin"),
            Provider = new CookieAuthenticationProvider
            {
                OnValidateIdentity = SecurityStampValidator.OnValidateIdentity<ApplicationUserManager, User>(
                    validateInterval: TimeSpan.FromDays(30),
                    regenerateIdentity: (manager, user) => user.GenerateUserIdentityAsync(manager))
            }
        });

        app.UseExternalSignInCookie(DefaultAuthenticationTypes.ExternalCookie);

        app.UseSaml2Authentication(new Saml2AuthenticationOptions(true));

I am using this same controller for logging out both SAML authenticated users, as well as the standard in-app username/password authenticated users.

For the SAML user, the logoff works with no issues.

When logging out non-SAML users it makes its way through all of the middleware, it successfully executes the controller, thus logging out successfully but following this, it spits out this exception.

I'm having some difficulty debugging this but I believe the issue might be occurring in Sustainsys.Saml2.WebSSO.LogOutCommand.InitiateLogout where claims such as SessionIndex are looked up, but of course does not exist as the user didn't authenticate with SAML.

I'm guessing the authentication handler should not even hit this code block if the user isn't SAML authenticated.

Am I missing some configuration to enable non-SAML users alongside SAML users?

The exception is really strange here so I could be way off base with this.