So as I mentioned in YouTube versus 360 degree cameras, I had problems getting the full resolution version of a 5K 360 video. Subsequently, I uploaded a 360 4K video on the 2nd, and YouTube told me it had finished processing SD, HD and 4K version in a short time, but it wouldn’t show me the 4K version. Even 6 days later, still no 4K. I just uploaded it again, and it finished processing SD, HD and 4K versions in less than an hour. And I could immediately see the 4K version of that one. Very annoying.
I don’t know if it’s significant or not, but the first time I uploaded was on Firefox and the second was on Chrome.