If it's an UltraWide 5K2K display, then why does the EDID not show any 5K modes? Maybe doesn't matter, since early Intel GPUs (before SkyLake) can't do 5K width anyway.
Try setting the display to DisplayPort 1.1 mode.
Here's a list of 64:27 modes capped at 5120 width, 75Hz, 270 MHz.
Code:
for ((x=5120;x>=1920;x-=128)); do
((y=$x*2160/5120))
for ((fps=75;fps>10;fps--)); do
result=$(edid-decode -S --cvt w=$x,h=$y,fps=$fps,rb=1)
if (($(perl -pE 's/.* (\d+)\.(\d+) MHz .*/$1$2/' <<< "$result") <= 270000000)); then
echo "$result"
break
fi
done
done
CVT: 5120x2160 22.980492 Hz 64:27 50.189 kHz 265.000000 MHz (RB)
CVT: 4992x2106 23.989043 Hz 64:27 51.097 kHz 263.250000 MHz (RB)
CVT: 4864x2052 24.976452 Hz 64:27 51.851 kHz 260.500000 MHz (RB)
CVT: 4736x1998 26.994288 Hz 64:27 54.636 kHz 267.500000 MHz (RB)
CVT: 4608x1944 27.999693 Hz 64:27 55.159 kHz 263.000000 MHz (RB)
CVT: 4480x1890 29.989162 Hz 64:27 57.489 kHz 266.750000 MHz (RB)
CVT: 4352x1836 31.984332 Hz 64:27 59.619 kHz 269.000000 MHz (RB)
CVT: 4224x1782 33.976016 Hz 64:27 61.531 kHz 269.750000 MHz (RB)
CVT: 4096x1728 35.986136 Hz 64:27 63.264 kHz 269.250000 MHz (RB)
CVT: 3968x1674 37.993424 Hz 64:27 64.741 kHz 267.250000 MHz (RB)
CVT: 3840x1620 39.975772 Hz 64:27 66.000 kHz 264.000000 MHz (RB)
CVT: 3712x1566 42.990205 Hz 64:27 68.698 kHz 266.000000 MHz (RB)
CVT: 3584x1512 45.985119 Hz 64:27 71.047 kHz 266.000000 MHz (RB)
CVT: 3456x1458 49.965844 Hz 64:27 74.599 kHz 269.750000 MHz (RB)
CVT: 3328x1404 52.959353 Hz 64:27 76.261 kHz 266.000000 MHz (RB)
CVT: 3200x1350 56.970337 Hz 64:27 79.018 kHz 265.500000 MHz (RB)
CVT: 3072x1296 61.997070 Hz 64:27 82.766 kHz 267.500000 MHz (RB)
CVT: 2944x1242 66.971107 Hz 64:27 85.857 kHz 266.500000 MHz (RB)
CVT: 2816x1188 72.941254 Hz 64:27 89.718 kHz 267.000000 MHz (RB)
CVT: 2688x1134 74.931269 Hz 64:27 88.044 kHz 250.750000 MHz (RB)
CVT: 2560x1080 74.991458 Hz 64:27 83.915 kHz 228.250000 MHz (RB)
CVT: 2432x1026 74.946576 Hz 64:27 79.668 kHz 206.500000 MHz (RB)
CVT: 2304x972 74.962277 Hz 64:27 75.487 kHz 186.000000 MHz (RB)
CVT: 2176x918 74.948144 Hz 64:27 71.276 kHz 166.500000 MHz (RB)
CVT: 2048x864 74.892721 Hz 64:27 67.029 kHz 148.000000 MHz (RB)
CVT: 1920x810 74.923214 Hz 64:27 62.861 kHz 130.750000 MHz (RB)
Maybe the maximum width the iGPU can do is 4096 so you should start there. Make sure you're using the CVT-RB option to calculate the timings in SwitchResX.
2688x1134 is the maximum size supporting 75 Hz.
3072x1296 is the maximum size supporting 60 Hz.
The EDID says the minimum refresh rate is 48 Hz, so that would excluding everything above 3456x1458 50Hz.
3440x1440 is not the same aspect ration as 5120x2160 so I'm not sure why the EDID would have this mode except that it's very close to the 48 Hz 270 MHz limit of 3456x1458 50Hz.
3440x1451 or 3413x1440 matches the 5120x2160 aspect ratio more closely than 3440x1440 does.
The EDID says the maximum refresh rate is 61 Hz. The specs page says it's 75Hz
https://www.lg.com/us/business/computer-monitors/lg-34BK95U-W
Maybe this EDID came from the HDMI port? We need the EDID from the DisplayPort port of the display.
Use
AllRez to get display info for both the DisplayPort input and the HDMI input of the display. If the display uses the same date or product ID for both ports then that could confuse SwitchResX.
