Just found the FTAN markup in the Pages.htt file.
Can you explain what this is and why it is added?
This is the implementation of a transaction token only, which prevents your site from CSFR and similar things.
All you have to do is: insert the {FTAN} placeholder in any form of your theme-template. Best to place is the line after the <form...> html token.
Thats all.
You can use wb_theme as example to see how to do.
Without these placeholders backend themes in the future no longer work.