17.0.1 retains cookies with Optons >> Privacy >> Always User Private Browing Mode Selected.
All sessions with secure sites (i.e. Windows Live) are retained after exit. I have tried browser.sessionstore.privacy_level at 0 (as set when selecting "Always Use Private Browsing Mode", 1, and 2, with no change.
Any ideas would be welcomed as this creates risk I am not willing to accept.