Ok, that sounds the same as my last processes. I usuall do a check with fastboot get_unlock_ability and do fastboot oem unlock and co. But I know that with the last two flashing episodes, I just used the ubports installer and the SFOS flash script.
Second point is the same for me, the different messages are the different partitions being written. This was on the VollaOS install, correct?
Could you post the contents of
~/.cache/ubports
please?