I've done a search investigating why my GoPro videos in 4K are not recognized by LR Classic. Some sites say I need to convert with Cineform, but the program is not available. I used a 3rd party to convert to MP4 (takes a long time) that is recognized by LR, but requires editing to original form.
So if I want to use LR to catalog my pics and videos, I need to be able to import GoPro videos.
I have no problem with 4K from my Canon 1DX in LR.