Strange Behaviour reflashing OPO Focal

[prophanetes]

UBports Installer 0.10.0 (snap)
Environment: Ubuntu Core 20 linux 5.15.0-71-generic x64 NodeJS v18.12.1
Device: bacon (Oneplus One)
Target OS: Ubuntu Touch
Settings: {"bootstrap":true,"wipe":true,"channel":"20.04/armhf/android9plus/devel"}
OPEN-CUTS run: N/A
Pastebin: https://snip.hxrsh.in/ubi-1683293821616

Background:
I'm on Focal R50. Trying to use installer to get beyond it (updating from within device doesn't find any - see https://forums.ubports.com/post/72954).

Issue:
Installer said 'rebooting into fastboot' but device stayed up - ignored the instruction to reboot.

Work around:
I manually restarted device, installer then updated to 'Flashing firmware' but actually the device just booted as normal.

Powered off again and used hardware keys to get into Recovery Mode, and forcing it to into Fastboot. Installer then resumed. (9 of 11 files downloaded and verified as I write this).