Logout and redirect to Form Login

Hi,

I have a very basic problem and found some articles and threads about it, but none seems to solve the issue.

I want to create a simple logout in a mashup which redirects the user back to the Thingworx form login. I am using Thingworx 9.2.1 and the standard "Logout" mashup function. The form login isn't a standard mashup so I am using the URL redirect.

Problem is: When I redirect to <hostname>/Thingworx/FormLogin/MyOrg the user can access Thingworx again without entering his username/password. This does not happen if I redirect to a different site (like google.com). But I can see that the user session is terminated in both cases.

I saw this article which try to explain the behaviour, but I did not understand it. And it's basically saying the exact opposite of that what I am observing.

Did I miss something obvious here?