I would like to know exactly what 'gap' means here but guessing, look at these two options

Sean Drohan
Stardock Support Manager

Thanks!

I did try the top of those two settings last night and it did not help. The gap is a phantom display when only two monitors are in the array

Eliminate every additional monitor for testing - just 1 on the primary and if the Secondary is a Laptop, just its own display, no additional monitor attached. 

Does it work then?  If so, at what point, adding one monitor at a time, does it fail?

Sean Drohan
Stardock Product Lifecycle Manager

If you can move your mouse onto what seems to be a phantom display (so more than a small amount of pixels) then that display exists somewhere.

Either Multiplicity has been told about another computer in the grid between the two you are controlling (and it is turned on - or InstantOn power saving), or there is another monitor either to the right of the primary or to the left of the secondary computer.

Multiplicity itself isn't able to create this effect on its own as once you hit the edge of the screen you physically cannot go any further.  An easy way to see which computer has the dummy display is to press the windows key when you are off the edge of the primary.  Whichever computer has the extra display will show the start menu.

Now that said there is another possibility which is you set the option to only switch when momentum is higher than a certain amount.  This would stop switches until the mouse moved quickly enough.

I found the problem. The "gap" was the closed laptop lid acting as a 3rd monitor.