Hi there,
Wow, Something is NOT right there. I myself have had only one " SOFT Brick/ Lock out" since the beginning(recovered with SWD NRF_Programmer- reported it as Locked,(my bad code suspected) I did an erase all first that unwedged it and I flashed the WatchFace.hex straight to it) went back to using the three west Commands and 100% repeatable and stable, I will make a video (desktop recording) doing my process you can see and comment perhaps there is an in between method that is more beginner friendly I agree.
I have created several projects all with the same way and no issue’s in any phases of the process getting to flashing, after it becomes a Rinse & Repeat 3 step. Yes always a -p pristine build 2nd, but I also remove any previous build remnants 1st the command "Remove-Item " may not be needed but i saw it on the Dev academy demo and adopted it ever since.
PITA for debugging SWD, OpenOCD, Seeed Debugger(OpenOcd wrapper) I haven’t arrived at a firm choice WIP
I want to update the “Grab Me” and "IMU Park w/sleep demo also so thanks for the head start 
and I got the full ROLO watch going and I’ll post it up with code.
HTH
GL 
PJ 