I think I might have hit this finally. The blank purple screen with a mouse cursor probably means the shell failed to start. And indeed I have no gnome-shell process running for my UID. The journalctl shows:
pr 23 14:33:47 haz gnome-shell[912]: g_dbus_connection_call_sync_internal: assertion 'G_IS_DBUS_CONNECTION (connection)' failed
I think I might have hit this finally. The blank purple screen with a mouse cursor probably means the shell failed to start. And indeed I have no gnome-shell process running for my UID. The journalctl shows:
pr 23 14:33:47 haz gnome-shell[912]: g_dbus_ connection_ call_sync_ internal: assertion 'G_IS_DBUS_ CONNECTION (connection)' failed