Hi
I am using V2.85 64 bit linux
I have checked the autoshutdown, close tixati when all downloads have finished, also checked persist after restart ( which it does ), but sadley when a download reached 100 % nothing happens, In the past I have used shutdown system which has worked.

are you sure ALL torrents have completed?
are you sure your computer(something running?) is not preventing tixati from shutting down your computer

just to be sure its not because you have an older version, get the newest version which is 2.86
https://www.tixati.com/download/