Experiencing very similar problem myself.
Otherwise absolutely adore this program. It's incredible.
Master: Windows 10 Enterprise 2015 LTSB (10.0.10240 Build 10240)
Slave: Windows 8.1 Pro (6.3.9600 Build 9600)
Master: dual monitors (external screens)
Slave: single monitor (laptop screen)
Mouse: Evoluent VerticalMouse 4 (Driver: c:\windows\system32\drivers\hidusb.sys (10.0.10240.16384, 37.50 KB (38,400 bytes), 10/07/2015 8:59 PM)
When I scoll on the slave system, fairly quickly but not immediately, the cursor moves to the bottom right of the slave desktop, give or take a few pixels and then very quickly to the bottom right of first of the dual monitors.
msinfo32 Components > Input > Pointing Device details on the Master setup:
http://i.imgur.com/spcwQxb.pngI dont exactly have a different mouse to try but I can try to arrange one if it would help.