Mouse move events stop working on transparent views

I want to implement a behavior similar to unhiding the dock macOS.

So I added a borderless transparent window snapped to the side of the screen. It has a transparent click-trough NSView to track mouse position. When mouse stays in the same position of this tracking view for some milliseconds, I show a content view.

The problem is that mouse move events are not showing up consistently. I receive some mouse move events and then they stop working.

The problem doesn't happen if the view has a layer with a non transparent color.

Any ideas? Thanks!
Mouse move events stop working on transparent views
 
 
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