This occurs whether or not Wayland is enabled. Is this an RTFM that I missed?
sudo tail -f messages| grep -i boxes
Jan 23 16:29:00 kerb-1 dbus-daemon[2769]: [session uid=1000 pid=2769] Activating service name='org.gnome.Boxes' requested by ':1.15' (uid=1000 pid=3256 comm="/usr/bin/gnome-shell ")
Jan 23 16:29:00 kerb-1 dbus-daemon[2769]: [session uid=1000 pid=2769] Successfully activated service 'org.gnome.Boxes'
Jan 23 16:29:00 kerb-1 org.gnome.Boxes[16599]: xkbcommon: ERROR: Key "<CAPS>" added to modifier map for multiple modifiers; Using Control, ignoring Lock
Jan 23 16:29:00 kerb-1 dbus-daemon[1499]: [system] Activating via systemd: service name='org.freedesktop.hostname1' unit='dbus-org.freedesktop.hostname1.service' requested by ':1.897' (uid=1000 pid=16599 comm="/usr/bin/gnome-boxes --gapplication-service ")
Jan 23 16:29:02 kerb-1 kernel: gnome-boxes[16599]: segfault at 0 ip 00007fc197e75e9c sp 00007ffd3a3c2e10 error 4 in libgio-2.0.so.0.5600.4[7fc197dcf000+1a0000]
Jan 23 16:29:05 kerb-1 systemd-coredump[17113]: Resource limits disable core dumping for process 16599 (gnome-boxes).
Jan 23 16:29:05 kerb-1 systemd-coredump[17113]: Process 16599 (gnome-boxes) of user 1000 dumped core.