I have found that STABILISATION isn't working in 12.12.1 (Windows portable version). It seems to have been broken in 12.12.0.
[More generally, the welcome cycle of adding features and fixing bugs is spoilt, nearly every time sadly, by regressions, making the software unreliable - sometimes unusable - in a working environment.]

just tried with latest build ( https://binary-factory.kde.org/job/Kden ... 64-gcc.exe ) on Windows 11... and the stabilization job is working.

Thank you bartoloni. I was using the PORTABLE version which IS broken.
Your link was to the INSTALL version which works (I'm on Windows 10 btw).
So that was a good pointer but something that might be looked at by the devs perhaps?

are you using the portable one on an "user" folder? like documents or download or on a different path? (like c:\ ... program files ... )