I upgraded Tumbleweed a few days ago, currently on cpe:/o:opensuse:tumbleweed:20170619.

I seem to have lost the ability to switch (graphical) users from the lock screen on the first session (Ctrl+Alt+F7).

It is still possible to open a new session via krunner (Alt F2, type "session", or "switch", …), however at the moment it does not appear to be possible for a second user to start a new session if the first user has walked away from the computer (and obviously, locked his session).

Anyone have any idea what might have changed and how to get the proper behaviour back?