If you take a look at the link below I have recorded a short screencast.Mic Posistion Issue Demo
The only thing I can see that looks wrong is:
Underneath the MIX tab label (to the right of all the Mic channels) you have the PRESET option to choose different Microphone Arrays.
I suggest switching through a couple of those choices and see if that works.
Your screen shows the PRESET name to be in a Black coloured font whereas they are always a fairly unreadable White colour on my screen.