Hello,
USB 3.0 device after reboot fails at address phase: |7f247000| xhci_alloc_pipe: address device: failed (cc -1)
I have encountered many of such problems with USB 3.0 devices and my conclusion is: no fix. For example see: https://github.com/pcengines/apu2-documentation/blob/master/docs/debug/usb-d...
For some platforms SeaBIOS will work perfectly all the time, for some you have to adjust timeouts for almost each different stick... It must be noted that SeaBIOS has very basic implementation of threads. USB devices are also initialized in threaded manner. Because of that it may introduce another timing issues. And as you already pointed, usb 2.0 ports are much more error proof.
Different stick may also behave in a different way, cause different errors. Some of them respond to commands earlier, some of them later.
If you really need to reliably boot from USB, use USB 2.0 port or change the stick model. That's my few months long experience with USB 3.0 sticks in SeaBIOS.
Regards,