Problem w/ 4K monitor -- mouse keeps jumping back

[Joel 0]

I'm in a situation where Synergy tries to switch from my primary desktop (MACHINE1) to my laptop (MACHINE2) but immediately jumps back to my desktop without passing the mouse/keyboard over to the laptop. My primary desktop (MACHINE1) is a multi-monitor rig running Windows 7 64-bit. The left monitor is an Acer 4K monitor running at 3840x2160. The right monitor is a normal wide-screen monitor running at 1920x1200. Windows 7 identifies the left monitor as "1" and the right monitor as "2", with the left monitor as my main display. For Windows 7 display layout purposes, the right monitor is logically smaller and located more or less vertically centered along the right side of the left monitor. Furthermore, since the 4K monitor text is tiny I have Windows "Appearance and Personalization" > "Display" set up to use 150% larger text (even though that looks really big on the normal right-side monitor). Synergy is configured so that my laptop (MACHINE2) is logically to the immediate right of my desktop. The laptop is also a Windows 7 64-bit machine. Whenever I move the mouse past the right border of my right monitor to switch to the laptop, rather than switching it instead jumps back to a position near the right edge of my left desktop monitor. [2016-07-12T09:09:20] INFO: switch from "MACHINE1" to "MACHINE2" at 0,695 [2016-07-12T09:09:20] INFO: leaving screen [2016-07-12T09:09:20] INFO: switch from "MACHINE2" to "MACHINE1" at 3555,607 [2016-07-12T09:09:20] INFO: entering screen This used to work before I got the 4K monitor. I used to have two "normal" monitors configured the same way except that Windows was running with text at 100% normal size, and the monitor "1" and "2" identities may have been swapped (though "main display" was always the left monitor). So I'm assuming that something changed in the new configuration is behind this.