Got this from ARTURIA SUPPORT today (thanks for the fast answer !)
"...This is not a hardware fault.
We have users having tune issues because most of them are touching the synth while tuning.
The tuning procedure can last up to 20-30 seconds. (The screen doesn't display "tune" during the whole procedure but only for around 5 seconds.)
If you press keys / change patch, change parameters while tuning, it may completely mess the tune process.
I advise to turn OFF / ON The synth, leave it warming up for around 15/20 minutes and then start a tune process.
Then do not touch the synth for a minute (to be sure it is correctly done)
Then try again.
On the next firmware update, the tune has been highly improved and the synth is locked during the tune process to avoid any issue...."
gonna try this tonight, would explain a lot, last but not least, why i somehow can recall the first not correct sounding patches (except 2 or 3)
good news, i really like this synth a lot !
in case you don't know yet, check out ARTUR FUSSY's great patches on youtube - great job !