No, you cannot on bankroll investments because your principal is included in your daily (gross) profit.
However you can stake your funds on Winza through the "HODL program" in order to divest anytime.
We have not faced any session issue so far, sessions last up to 24 hours. What is your current setup? Mobile?
how long does it take to divest from the normal bankroll? or are you saying principal gets stuck forever?
and i am on desktop trying from chrome, microsoft edge, and brave. all of them are logging out after 30 minutes of inactivity or so but it is only happening here