I'm not sure comment #6 is the same bug. Here's what one of my affected ThinkPads does. Plymouth can't find working graphics (race condition with something??) and reverts to text mode:

00:00:07.541 ply-device-manager.c:917:create_devices_from_udev             : Timeout elapsed, looking for devices from udev
00:00:07.541 ply-device-manager.c:331:create_devices_for_subsystem         : creating objects for drm devices
00:00:07.542 ply-device-manager.c:351:create_devices_for_subsystem         : found device /sys/devices/pci0000:00/0000:00:02.0/drm/card0
00:00:07.542 ply-device-manager.c:374:create_devices_for_subsystem         : it's not initialized
00:00:07.542 ply-device-manager.c:351:create_devices_for_subsystem         : found device /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-DP-1
00:00:07.542 ply-device-manager.c:374:create_devices_for_subsystem         : it's not initialized
00:00:07.542 ply-device-manager.c:351:create_devices_for_subsystem         : found device /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-DP-2
00:00:07.542 ply-device-manager.c:374:create_devices_for_subsystem         : it's not initialized
00:00:07.542 ply-device-manager.c:351:create_devices_for_subsystem         : found device /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-HDMI-A-1
00:00:07.542 ply-device-manager.c:374:create_devices_for_subsystem         : it's not initialized
00:00:07.542 ply-device-manager.c:351:create_devices_for_subsystem         : found device /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-HDMI-A-2
00:00:07.542 ply-device-manager.c:374:create_devices_for_subsystem         : it's not initialized
00:00:07.542 ply-device-manager.c:351:create_devices_for_subsystem         : found device /sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1
00:00:07.542 ply-device-manager.c:374:create_devices_for_subsystem         : it's not initialized
00:00:07.542 ply-device-manager.c:351:create_devices_for_subsystem         : found device /sys/devices/pci0000:00/0000:00:02.0/drm/renderD128
00:00:07.542 ply-device-manager.c:374:create_devices_for_subsystem         : it's not initialized
00:00:07.542 ply-device-manager.c:331:create_devices_for_subsystem         : creating objects for frame buffer devices
00:00:07.542 ply-device-manager.c:351:create_devices_for_subsystem         : found device /sys/devices/pci0000:00/0000:00:02.0/graphics/fb0
00:00:07.542 ply-device-manager.c:374:create_devices_for_subsystem         : it's not initialized
00:00:07.542 ply-device-manager.c:351:create_devices_for_subsystem         : found device /sys/devices/virtual/graphics/fbcon
00:00:07.542 ply-device-manager.c:374:create_devices_for_subsystem         : it's not initialized
00:00:07.542 ply-device-manager.c:925:create_devices_from_udev             : Creating non-graphical devices, since there's no suitable graphics hardware
00:00:07.542 ply-device-manager.c:786:create_devices_for_terminal_and_rende: creating devices for  (renderer type: 4294967295) (terminal: /dev/tty1)
00:00:07.542 main.c:1001:on_keyboard_added                                 : listening for keystrokes
00:00:07.542 main.c:1005:on_keyboard_added                                 : listening for escape
00:00:07.542 main.c:1009:on_keyboard_added                                 : listening for backspace
00:00:07.542 main.c:1013:on_keyboard_added                                 : listening for enter
00:00:07.542 ply-terminal.c:637:ply_terminal_open                          : trying to open terminal '/dev/tty1'
00:00:07.542 ply-terminal.c:430:ply_terminal_refresh_geometry              : looking up terminal text geometry
00:00:07.542 ply-terminal.c:442:ply_terminal_refresh_geometry              : terminal is now 240x67 text cells
00:00:07.542 ply-terminal.c:480:get_active_vt                              : Remembering that initial vt is 7
00:00:07.542 ply-device-manager.c:759:create_text_displays_for_terminal    : adding text display for terminal /dev/tty1