It was disabled due to bug 1421443. Now with Xubuntu 19.10 and the switch to xfce4-screensaver it may be possible to enable it again. Note that this new change only disables the lock setting, and not the autostart entry.
https://git.launchpad.net/xubuntu-default- settings/commit/?id=650fd90df8d1e3e7b15fd789907fa47e9e2f68e5 ** Package changed: xubuntu-meta (Ubuntu) => xubuntu-default-settings (Ubuntu) -- You received this bug notification because you are a member of Xubuntu Developers, which is subscribed to xubuntu-default-settings in Ubuntu. Matching subscriptions: xubuntu-default-settings https://bugs.launchpad.net/bugs/1835668 Title: Locking screen on live system no longer possible with Xubuntu 18.10/19.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xubuntu-default-settings/+bug/1835668/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~xubuntu-dev Post to : xubuntu-dev@lists.launchpad.net Unsubscribe : https://launchpad.net/~xubuntu-dev More help : https://help.launchpad.net/ListHelp