I have noticed that after about 45-60 mins of working, the menus in the editor will flicker, or appear for a moment and then vanish. This happens on the main editor windows and inside the Event Graph when selecting nodes. I have tried rolling back my video card driver (Nvidia - was using the latest Studio Driver and rolled back, now using the latest Game Ready Drivers). I have only noticed this bug within the last month or so, but I have been using UE4 a lot more recently, so it could have been around for longer. It’s a pain as I have to keep hitting CTRL+SHIFT S and reload the Editor.