I am facing a similar problem, but unlike the case of the bug reporter, in my case it happens when "double-click on top bar of window to minimize" feature is not enabled. I have never enabled that feature.
I'd like to emphasize that in my case if right behind the titlebar there is another window (not desktop), the double click on the titlebar is not transferred to that window or to desktop.
I am facing a similar problem, but unlike the case of the bug reporter, in my case it happens when "double-click on top bar of window to minimize" feature is not enabled. I have never enabled that feature.
My original description of the bug: https:/ /bugs.launchpad .net/bugs/ 1888975
I'd like to emphasize that in my case if right behind the titlebar there is another window (not desktop), the double click on the titlebar is not transferred to that window or to desktop.