Example: I want to drag a photo to imessage. Normally I would go to the desktop, drag an item to the app in the bottom bar with all my application, I hold the file over the app. I can now wait a few seconds or press space bar to see all the open windows of the app. Then hold the file over the window I want to drop the file in and wait or press space again. In sierra this worked for a short while but now every time when I hold the file over the app and press space but nothing happens. If I just wait, the app flashes a feq times, which normally would indicate that it would show me all open windows, but nothing happens from then on. Edit: I think it only works one time per app (and even then sometimes it doesn’t work properly, eg I cant actually drop the file or something), but atleast the first time the app comes up. When I’ve already tried it it doesn’t work at all anymore.