1) You can try adding Uppercut
from https://forum.xda-developers.com/lg-g5/development/uppercut-lgup-loader-g5-variants-t3511295 Note
: Must use LGUP version 1.14
2) If you are not using LGUP-NEW
download from https://forum.xda-developers.com/g4/help/lgup-install-kdz-mm-lp-t3249803
and use that version. Recommended version to use
3) If you are using LGUP-NEW
already, then your alternative will be to use the LG Flash Tool 2014
from https://forum.xda-developers.com/showthread.php?t=2797190 Note
: You should be very sure that you are flashing a known and proven KDZ, i.e., one preferably that you have used before with no problems, otherwise you run the risk of hard-bricking your device. If you bought your phone 2nd hand or it is a refurbished model, it is possible that you do not have the model you think you do - only way to be really sure is to pull the phone apart and get the model number off the motherboard.
Make sure that you have the LG Mobile driver installed on your PC/Laptop before trying any of the above - it can be removed in certain instances and replaced with a generic one that doesn't allow full functioning or recognition of your device. Check in 'Device Manager' to confirm.
I ran into a similar issue to what you're experiencing after a harder soft brick with LGUP-NEW not recognizing my phone - option 3 was my last shot before sending it in for repair. The LG Flash Tool was the only thing that worked - it didn't recognize the phone but when I started the flash it worked perfectly - However, I did have a known KDZ that I had used before a few times with LGUP-NEW when it recognized and worked before. LGUP-NEW worked perfectly again after using the tool to flash the kdz.