@Tim - Could you check the ntp apparmor profile if it has the change that was made in 1:4.2.8p10+dfsg-5ubuntu4 ?
It is a conffile so if depending on your former changes it might have been not updated by default.
Essentially if /etc/apparmor.d/usr.sbin.ntpd has flags=(attach_disconnected) ?
@Tim - Could you check the ntp apparmor profile if it has the change that was made in 1:4.2.8p10+ dfsg-5ubuntu4 ?
It is a conffile so if depending on your former changes it might have been not updated by default.
Essentially if /etc/apparmor. d/usr.sbin. ntpd has flags=( attach_ disconnected) ?