Only one of external monitors works (Lenovo T480 on Ubuntu 18.04)

I have two external monitors connected to Lenovo T480 via USB-C and HDMI ports (no adapters). The system only detects builtin and external monitor connected via USB-C, the one connected via HDMI - turns black and nothing happens. But when I unplug USB-C monitor, then HDMI one starts working and the system recognizes it. Btw closing the lid didn't help - the situation is the same - only USB-C works (HDMI works only if USB-C disconnected).

lspci -v | grep -i vga:

00:02.0 VGA compatible controller: Intel Corporation UHD Graphics 620 (rev 07) (prog-if 00 [VGA controller])

lshw -c video

  *-display                 
       description: VGA compatible controller
       product: Intel Corporation
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 07
       width: 64 bits
       clock: 33MHz
       capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:154 memory:e7000000-e7ffffff memory:c0000000-cfffffff ioport:e000(size=64) memory:c0000-dffff

xrandr with USB-C connected (HDMI connected):

Screen 0: minimum 320 x 200, current 3840 x 1200, maximum 8192 x 8192                         
eDP-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x 174mm        
   1920x1080     60.02*+  60.01    59.97    59.96    59.93    48.00                           
   1680x1050     59.95    59.88                                                               
   1600x1024     60.17                                                                        
   1400x1050     59.98                                                                        
   1600x900      59.99    59.94    59.95    59.82                                             
   1280x1024     60.02                                                                        
   1440x900      59.89                                                                        
   1400x900      59.96    59.88                                                               
   1280x960      60.00           
   1440x810      60.00    59.97  
   1368x768      59.88    59.85  
   1360x768      59.80    59.96  
   1280x800      59.99    59.97    59.81    59.91  
   1152x864      60.00  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   800x512       60.17  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   720x450       59.89  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   684x384       59.88    59.85  
   680x384       59.80    59.96  
   640x400       59.88    59.98  
   576x432       60.06  
   640x360       59.86    59.83    59.84    59.32  
   512x384       60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 1920x1200+1920+0 (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200     59.95*+
   1920x1080     60.00  
   1600x1200     60.00  
   1680x1050     59.95  
   1280x1024     60.02  
   1280x960      60.00  
   1024x768      60.00  
   800x600       60.32  
   640x480       59.94  
   720x400       70.08  
HDMI-2 disconnected (normal left inverted right x axis y axis)

xrandr with USB-C disconnected (HDMI connected):

Screen 0: minimum 320 x 200, current 3840 x 1200, maximum 8192 x 8192
eDP-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x 174mm                                                   

   1920x1080     60.02*+  60.01    59.97    59.96    59.93    48.00                                                                                                                           
   1680x1050     59.95    59.88                                                                                                                                                               
   1600x1024     60.17                                                                                                                                                                        
   1400x1050     59.98                                                                                                                                                                        
   1600x900      59.99    59.94    59.95    59.82                                                                                                                                             
   1280x1024     60.02                                                                                                                                                                        
   1440x900      59.89                                                                                                                                                                        
   1400x900      59.96    59.88
   1280x960      60.00  
   1440x810      60.00    59.97  
   1368x768      59.88    59.85  
   1360x768      59.80    59.96  
   1280x800      59.99    59.97    59.81    59.91  
   1152x864      60.00  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   800x512       60.17  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   720x450       59.89  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   684x384       59.88    59.85  
   680x384       59.80    59.96  
   640x400       59.88    59.98  
   576x432       60.06  
   640x360       59.86    59.83    59.84    59.32  
   512x384       60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected primary 1920x1200+1920+0 (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200     59.95*+
   1920x1080     60.00  
   1600x1200     60.00  
   1680x1050     59.88  
   1280x1024     60.02  
   1280x960      60.00  
   1024x768      60.00  
   800x600       60.32  
   640x480       59.94  
   720x400       70.08

enter image description here


Solution 1:

I had a similar issue (even though I use Windows) on the T480 using a USB-C hub with HDMI, power and other USB ports.

In my case, the problem was I was using the wrong USB-C port. I was using the left-most USB-C which powers the laptop, instead of the second from the left which is the only Thunderbolt capable one.

Hope this helps, at least someone else who might come across this post.