Multiplicity Hotkey Sequence Erroneously Firing

I'm a relatively new Multiplicity user, and am configuring it to have a hotkey switch back to the primary.  I often use Multiplicity on a setup where my secondaries have a kernel debugger that breaks in some time.  I've configured Multiplicity to use the same hotkey I used in a different virtual KVM system (Ctrl-Shift-Alt-Insert) so I don't have to wait on a timeout to switch back to the primary.

The problem that I'm seeing is that the hotkey is firing when it shouldn't.  If I have focus on the secondary and type Shift-Insert, without pressing either Ctrl or Alt, focus returns to the primary.  It appears that the problem is specific to the Shift modifier -- no switch occurs on Ctrl-Insert, Alt-Insert, and Ctrl-Alt-Insert.  I do get a switch for Ctrl-Shift-Insert and Alt-Shift-Insert also.

My full hotkey configuration is:
Hotkey to press:  Ctrl+Shift+Alt+Insert
Switch to this computer:  PRIMARY computer
Position the mouse cursor at:  ... Do not alter mouse position checked

I'm working around this by switching to a less commonly-used key (KP_Minus).