Ubuntu 19.04; no se muestra ninguna pantalla de inicio de sesión gráfica automática en el arranque

Ubuntu 19.04; no se muestra ninguna pantalla de inicio de sesión gráfica automática en el arranque

Recientemente hice una instalación nueva de Ubuntu 19.04. Desde entonces, cuando inicio mi máquina aparece una pantalla que muestra el registro de inicio, pero no cambio a la pantalla de inicio de sesión.

Puedo iniciar manualmente la pantalla de inicio de sesión presionando [CTRL][ALT][F2] seguido de [CTRL][ALT][F1].

¿Cómo puedo hacer que la pantalla de inicio de sesión aparezca automáticamente?

El registro de arranque (de /var/log/boot.log, pero que coincide con lo que veo durante el arranque) es:

[  OK  ] Started Tell Plymouth To Write Out Runtime Data.
[  OK  ] Reached target System Initialization.
[  OK  ] Started Discard unused blocks once a week.
[  OK  ] Started CUPS Scheduler.
[  OK  ] Started Trigger anacron every hour.
[  OK  ] Listening on Activation socket for spice guest agent daemon.
         Starting Socket activation for snappy daemon.
[  OK  ] Listening on ACPID Listen Socket.
[  OK  ] Started Daily rotation of log files.
[  OK  ] Started Daily man-db regeneration.
[  OK  ] Listening on UUID daemon activation socket.
[  OK  ] Started ACPI Events Check.
[  OK  ] Reached target Paths.
[  OK  ] Started Message of the Day.
[  OK  ] Listening on D-Bus System Message Bus Socket.
[  OK  ] Listening on Avahi mDNS/DNS-SD Stack Activation Socket.
[  OK  ] Started Daily Cleanup of Temporary Directories.
[  OK  ] Listening on CUPS Scheduler.
[  OK  ] Started Daily apt download activities.
[  OK  ] Started Daily apt upgrade and clean activities.
[  OK  ] Reached target Timers.
[  OK  ] Listening on Socket activation for snappy daemon.
[  OK  ] Reached target Sockets.
[  OK  ] Reached target Basic System.
         Starting Accounts Service...
         Starting LSB: Record successful boot for GRUB...
         Starting Avahi mDNS/DNS-SD Stack...
[  OK  ] Started ACPI event daemon.
         Starting Disk Manager...
[  OK  ] Started irqbalance daemon.
         Starting Switcheroo Control Proxy service...
         Starting Bluetooth service...
         Starting Rotate log files...
         Starting Login Service...
[  OK  ] Started Run anacron jobs.
         Starting LSB: automatic crash report generation...
         Starting Dispatcher daemon for systemd-networkd...
[  OK  ] Reached target Login Prompts.
[  OK  ] Started Save initial kernel messages after boot.
         Starting Detect the available GPUs and deal with any system changes...
[  OK  ] Reached target Sound Card.
         Starting System Logging Service...
         Starting Modem Manager...
         Starting Daily man-db regeneration...
[  OK  ] Started D-Bus System Message Bus.
         Starting Network Manager...
         Starting WPA supplicant...
[  OK  ] Started Regular background program processing daemon.
         Starting Configure Plugged-In Printer...
         Starting Thermal Daemon Service...
[  OK  ] Started CUPS Scheduler.
[  OK  ] Reached target Printer.
         Starting Restore /etc/resolv.conf if the system crashed before the ppp link was shut down...
[  OK  ] Started Set the CPU Frequency Scaling governor.
         Starting Snappy daemon...
[  OK  ] Started Switcheroo Control Proxy service.
[  OK  ] Started Restore /etc/resolv.conf if the system crashed before the ppp link was shut down.
[  OK  ] Started Login Service.
[  OK  ] Started LSB: Record successful boot for GRUB.
[  OK  ] Started LSB: automatic crash report generation.
[  OK  ] Started Detect the available GPUs and deal with any system changes.
[  OK  ] Started Bluetooth service.
[  OK  ] Started WPA supplicant.
[  OK  ] Started Thermal Daemon Service.
[  OK  ] Started System Logging Service.
[  OK  ] Started Avahi mDNS/DNS-SD Stack.
[  OK  ] Started Make remote CUPS printers available locally.
         Starting Manage, Install and Generate Color Profiles...
[  OK  ] Reached target Bluetooth.
         Starting Authorization Manager...
[  OK  ] Started Dispatcher daemon for systemd-networkd.
         Starting Hostname Service...
[  OK  ] Started Authorization Manager.
[  OK  ] Started Hostname Service.
[  OK  ] Started Manage, Install and Generate Color Profiles.
[  OK  ] Started Network Manager.
         Starting Network Manager Wait Online...
[  OK  ] Reached target Network.
         Starting Permit User Sessions...
         Starting OpenVPN service...
[  OK  ] Started Unattended Upgrades Shutdown.
[  OK  ] Started OpenVPN service.
         Stopping CUPS Scheduler...
[  OK  ] Stopped CUPS Scheduler.
[  OK  ] Started CUPS Scheduler.
[  OK  ] Started Permit User Sessions.
         Starting GNOME Display Manager...
         Starting Hold until boot process finishes up...
         Starting Network Manager Script Dispatcher Service...
[  OK  ] Started Network Manager Script Dispatcher Service.
[  OK  ] Started Modem Manager.
[  OK  ] Started GNOME Display Manager.

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