If I use cmd-Q to quit an app, then because some apps take a second or two to quit, I can bring up the Alfred window (cmd-space for me), sometimes, before the app closes. However, when the app then finishes closing, the Alfred window disappears as well.
This is a problem because I'm often already typing the next thing I want to do in Alfred, and it just vanishes in front of me.
Alfred 3.6.2
macOS 10.13.6