control: reassign -1 lxpolkit Thank you for reporting this.
Your issue seems as a lxpolkit configuration problem. Could you, please, look if there aren't two lxpolkit processes running at the moment when you are logged in? Could you also check if there is a policy kit agent checked on in the list of autostarted processes? You can see that in lxsession default apps configuration program on tab 'Autostart'. If it's checked on then please, check it off and then report if it fixes the issue. Thank you in advance.