I just purchased the latest revision of the 27in 5K (the one that supports 4K over USB-C), which I'm using with my 12 inch MacBook until I upgrade to a MacBook Pro later this year.
I have had no video issues with the USB-C to USB-C connection (since the 12in MacBook does not support Thunderbolt), but I've had pervasive issues with audio, webcam, and USB-C peripherals cycling in and out of connection (e.g. the audio output will switch from my laptop to the monitor speakers every 5-10 seconds, since the computer cycles between recognizing the USB connection of the monitor and not.
I've done SMC reset, NVRAM, factory reset, updated to Catalina etc to no avail, I can't get the connection to stick, not even to conduct a firmware update with the LG Screen Utility app. Could it be a faulty USB-C cable, or a broader issue? I'd like to determine whether or not this is an issue with my laptop or with the monitor, before purchasing a laptop only to find that the monitor is faulty.
If anyone has experienced this issue, I'd appreciate it if you could share your experience or any other solutions. Thanks!