The most recent beta 8 update (gnome 3.28.2-1) still yields random logouts and coredumps from Xwayland, gnome-shell, and pulseaudio. I also find that when I am logged out, sometimes the gnome environment fails to initialize, the desktop does not show up, I have to switch to another terminal and switch back. When I switch back, I've been logged out and can successfully login again.
# coredumpctl TIME PID UID GID SIG COREFILE EXE Tue 2018-06-19 20:56:10 EDT 2883 1000 1000 6 present /usr/bin/Xwayland Tue 2018-06-19 20:59:51 EDT 19635 1000 1000 6 present /usr/bin/Xwayland Tue 2018-06-19 20:59:57 EDT 20130 1000 1000 6 present /usr/bin/pulseaudio Tue 2018-06-19 21:00:46 EDT 20274 1000 1000 6 present /usr/bin/Xwayland Fri 2018-06-22 08:54:26 EDT 20838 1000 1000 6 present /usr/bin/Xwayland Fri 2018-06-22 08:54:27 EDT 20832 1000 1000 11 present /usr/bin/gnome-shell Fri 2018-06-22 08:54:32 EDT 30124 1000 1000 6 present /usr/bin/pulseaudio Sat 2018-06-23 08:09:01 EDT 30305 1000 1000 6 present /usr/bin/Xwayland Sat 2018-06-23 08:09:01 EDT 30288 1000 1000 11 present /usr/bin/gnome-shell