I have not made any dramatic changes to the mouse or trackpad settings, other than turning on most of the Trackpad Touch gestures.
As for what I used:
I have used both the trackpad, a standard Gaming Mouse, and a standard windows mouse.
It does the same thing as what you are seeing here.
After reading your reply, I wanted to see if changing my settings on my mouse and trackpad would do anything; so I turned off all of my Trackpad’s Touch gestures and for the mouse, changed the double click speed to a low setting. After which, I opened Unreal and tested it again, Unfortunately the same outcome occurs.