You are absolutely right ! Nothing wrong with recording. It played OK in camera, no damaged frames. Card reader is OK actually, when plugged to a fast USB 3.0 port it works OK
Problem was when card reader was on a slow USB2 port. Never had a problem with this USB 2 port. It was slow but worked.
Anyway, thanks for the help and apologies for bugging you with something that is way off ML
But sometimes it's just a bad day and my brain doesn't work as it should

By the way with kill global draw 3584x1730 (2:1 my favorite ratio) at 10 bit recording times are excellent. Way more that expected !
Again thanks a lot for your work and help.