Kernel problem. Older kernel version boots. Computer gets stuck at the blinking cursor on a black screen and virtual consoles are unavailable.
Update: this can be described as a boot hang. The boot messages say that a new USB device is found, then it hangs for a little less than a minute, then finally boots. Older kernels don’t do this.
This is what happened with me. I am back on LTS current and planning to stick with it. Only recently realised that playing with the ‘latest and greatest’ in the Linux world is like beta testing.