Second display works but doesn't appear

I tried connecting a secondary display to my laptop, and it seems to awkwardly half-work. I can’t figure out why, though.

Right now, the external monitor only lets me drag objects 90% of the way to the right (there’s a small sliver of the screen where I can place my cursor, but for some reason, I can’t have a fullscreen window there.

Moreover, when I try to fix the problem using the display settings, the second screen just doesn’t show up, even though it’s connected by HDMI and clearly working (apart from the minor issue mentioned).

Anyone know how to fix this?

Inxi:

(base) [lime@lime-public ~]$ inxi
CPU: 6-core Intel Core i7-10750H (-MT MCP-) speed/min/max: 1079/800/5000 MHz
Kernel: 6.4.16-6-MANJARO x86_64 Up: 15h 48m Mem: 10.28/15.49 GiB (66.4%)
Storage: 476.94 GiB (87.7% used) Procs: 394 Shell: Bash inxi: 3.3.30

xrandr:

(base) [lime@lime-public ~]$ xrandr
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 16384 x 16384
eDP-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1920x1080    120.00*+  60.01    59.97    59.96    59.93  
   1680x1050     59.95    59.88  
   1400x1050     74.76    59.98  
   1600x900      59.99    59.94    59.95    59.82  
   1280x1024     85.02    75.02    60.02  
   1400x900      59.96    59.88  
   1280x960      85.00    60.00  
   1440x810      60.00    59.97  
   1368x768      59.88    59.85  
   1280x800      59.99    59.97    59.81    59.91  
   1152x864      75.00  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      85.00    75.05    60.04    85.00    75.03    70.07    60.00  
   1024x768i     86.96  
   960x720       85.00    75.00    60.00  
   928x696       75.00    60.05  
   896x672       75.05    60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   832x624       74.55  
   960x540       59.96    59.99    59.63    59.82  
   800x600       85.00    75.00    70.00    65.00    60.00    85.14    72.19    75.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   700x525       74.76    59.98  
   800x450       59.95    59.82  
   640x512       85.02    75.02    60.02  
   700x450       59.96    59.88  
   640x480       85.09    60.00    85.01    72.81    75.00    59.94  
   720x405       59.51    58.99  
   720x400       85.04  
   684x384       59.88    59.85  
   640x400       59.88    59.98    85.08  
   576x432       75.00  
   640x360       59.86    59.83    59.84    59.32  
   640x350       85.08  
   512x384       85.00    75.03    70.07    60.00  
   512x384i      87.06  
   512x288       60.00    59.92  
   416x312       74.66  
   480x270       59.63    59.82  
   400x300       85.27    72.19    75.12    60.32    56.34  
   432x243       59.92    59.57  
   320x240       85.18    72.81    75.00    60.05  
   360x202       59.51    59.13  
   360x200       85.04  
   320x200       85.27  
   320x180       59.84    59.32  
   320x175       85.27  
DP-1-0 disconnected (normal left inverted right x axis y axis)
DP-1-1 disconnected (normal left inverted right x axis y axis)
HDMI-1-0 disconnected 1920x1080+1920+0 (normal left inverted right x axis y axis) 0mm x 0mm
DP-1-2 disconnected (normal left inverted right x axis y axis)
  1920x1080 (0x274) 148.500MHz +HSync +VSync
        h: width  1920 start 2008 end 2052 total 2200 skew    0 clock  67.50KHz
        v: height 1080 start 1084 end 1089 total 1125           clock  60.00Hz

And… bizarrely, it’s working perfectly now. I’ll report back if it happens again.