Dp3M . manual mode defective ? Help needed

Hello everyone

Let me first give you the big picture . I have been a photographer for 20 years and am familiar with the Sigma DP as I owned a dp2x

Despite my not liking 3;2 ratio only cameras , I bought a dp2m two weeks ago as a camera to carry on trips along with my m4/3rd camera system when shooting static subjects

For me the user interface is ALWAYS a big factor when choosing a camera because the best IQ is of no help if the UI is so clumsy that you never get comfortable with it ( this is why I do not like Fuji X's)

I always kind of like the dp simple user interface and along with the amazing IQ at low ISO..

As I am leaving in a few days for a BIG photo trip , I went out to check my camera and I found a BIG issue with my dp3m that I do not know what to make of

Whichever the camera , I always prefer to use the manual mode . but on the Dp3 m , there is something weird . the shutter speed changes AFTER each shot . I would expect the manual mode to behave like EVERY other manual  mode I have ever used, i.e that the shutter speed does not change unless you touch the dial that sets the shutter speed

but on my dp3m , it is changing  with every image or so. I thought for a while that maybe it goes back to whichever value the cell thinks is the theoritically correct shutter speed for the right exposure but NO. it will go from 1/200 to 1/60 even if the light does not change .

As I was testing the frame of the OVF , ( the correct exposure  value)did not matter that much  i would set the speed say at 200 to get the correct exposure value and then within  seconds , take 2 more pics without touching any button and then found out that it took the second one at 1/40 and then the next one at 1/500

I even checked the manual and saw nothing  that would explain that strange behavior . I even took out again my dp2x manual mode but NO everything is normal on the dp2x

This does seem to happen ONLY in manual mode

Did anyone here experienced similar issue on his or her dpm or has any idea of what may be going on ?

Please let me know if you have any idea ( and if you are just going to say use another mode , thanks but I do not need this "advice "

Thank you for your insight

H