"Click at found image" action not working the same with dual monitors

In the past, my setup has generally been to connect my MacBook Pro to my external display, and then to close my MacBook Pro, so that my external display is my only active display.

Recently, I've started using my MacBook Pro and external display side-by-side, with the external display set as my primary screen and the MacBook Pro set as my secondary screen.

KM macros that used to function just fine seem to have been thrown off by this. For example, with macros that include the "click at found image" action, this action often no longer works when the "in" selection is set to "the front window," even if the image in question is in fact in the front window. However, if I change the "in" selection from "the front window" to "all screens," the action and macro suddenly start working again, just as they used to.

Any idea what's going on here? Is this a KM bug?