Add me to the list.
Currently I've reluctantly solved by moving the SSD to the USB2 port, which nulls one of the main reasons for having chosen the Rock64. However, I have this idea that the problem is not the kernel, but u-boot which does not properly initialize the USB3 port. It is a fact that sometime you are able to boot from USB3, as long as you have no other current-dragging devices connected (included the HDMI cable). It is still a shot in the dark, i.e. will mostly fail, but if you have other devices connected, in my own experience, there is 0% possibility that the boot from USB3 succeeds.
And no, using an USB3 hub does not make any difference, I agree.