Hmmm.....I've been playing around trying to find a solution. Seems to be a mouse-mapping problem. When I turn on "Magic Mouse" so that I can see the windows pointer underneath the Amiga Pointer, I can see that the two pointers do not match up. The Windows Pointer is always offset from the Amiga Pointer. I wonder if this is part of the problem. (i.e. the windows pointer reaches the edge of the screen before the Amiga pointer does and so the computer says "stop the pointer from moving").
The offset of the Windows pointer matches exactly the amount of "Dead zone" border that the Amiga pointer won't move into at the edges of the Amiga screen.
Here is the offset if I disable all filters:
And if I enable Automatic Aspect Ratio Correction in FILTERS the offset changes to the other side of the Amiga pointer (and so the dead zone moves to the left edge of the Amiga screen).
Depending on what Amiga screenmode is chosen, the offset will always be different than other screenmodes (but consistent to that screenmode).
Is there any way to manually correct the offset of the two pointers?