My two monitors are identical, - so life here is much easier!
(Thank goodness!) .... Sorry!
In doing some more tests though, it would appear that this current version of MA3 is not happy when the screens are set at different resolutions, - but I can set them to a wrong/lower res,
(as long as they are both set the same), .... and I then have no problems!
But strange things can happen when the windowed mode is on the secondary monitor!
Ralph, - re: Your 'Part 2' post...
I really think that what I said
here is important re the connecting and settings of the two monitors, Primary v Secondary!