Some of the tags are for specific email types only. So [#login_details#] can be used in registration, activation and forgot password emails only and [#form_fields#] can be used with update account emails to users only. We are working on the email template system which will allow many of the tags used in all emails and specific tags on specific emails which will mostly be released in the next update.
This code should not do logout maybe some other issue and needs troubleshooting. Can you please create a similar user and provide username and password so that I can look into the issue? Also please whitelist my IP address 126.96.36.199. If you can explain the steps to regenerate the issue then it will help more.
To open a new support ticket, first select the relevant forum and then click the "New Post" button. Example: You need support for the core plugin? Click on Core Plugin support and click on the "New Post" Button.