@zk2004mb @CaseySJ I don't know if you're using the 2019 version of the LG UltraFine but I've had nothing but trouble with mine. I do not have a flashed Thunderbolt controller.
I do not have issues with the USB/Audio most of the time (not that I've ever tested the audio, it's just never been missing for me). Sometimes, on a hard power off/reset, the USB doesn't work but shutting off and starting again (I can tell preboot because my keyboard is plugged inth the USB-C hub so if I don't get any lights and/or can't move around in OpenCanopy I know).
Sometimes the monitor won't come on and I have to unplug the power cord and plug back in. This is generally only if I shut down and cold booted, and doesn't always happen.
More annoyingly,
I absolutely cannot boot with iGPU enabled (maybe turning iGPU off will help you). If I boot a 27 inch LG 4K monitor (non-TB, DP) I can boot with iGPU enabled no problem. Oddly, I can force the boot by booting into a different OS and warm rebooting, but when the PC goes to sleep, it will freeze on wake.
None of these issues occur without the UltraFine for me.
I've actually been having a lot of hard freezes, getting worse over time to the point (several per hour now to the point of being unusable) I am going to reinstall. I replaced my Samsung 970 Evo Plus with a Sabrent Rocket 4.0 but I got the freezes even if I boot my Samsung 860 Evo CCC backup (this was before the replacement, time will tell if my recent changes fixed the problem).
I'm actually testing now with no UltraFine 5K or Samsung 970 Evo Plus to see if I get the freezes, and am working off my backup (I have made additional backups in case something goes wrong here), but I started with CaseySJ's OC 0.6.0 and made a few changes to start fresh. I couldn't even boot the Catalina Installer with iGPU on without disconnecting the UltraFine (I have for awhile using iMacPro1,1+iGPU Off reluctantly, because months of trying to resolve this has been a failure.
I hope my freezes+KP are a result of the monitor as that means at least my install isn't ruined. That being said, that also means my UltraFine is a plague to my system that might not have a solution. Hoping I can run off my backup (if stable long enough I will restore to my new Sabrent Rocket 4.0), because I don't want to have to start from scratch on Catalina with Big Sur this close (I was going to clean install that anyway).