This has happened a handful of times before, but this time I got it on video! Pressing command+c to copy some text doesn't work sometimes. It doesn't matter if I select the text with the keyboard or mouse, it's as if the copy command just doesn't work. I did some testing with using the commands from the edit menu too.
Check out the video for proof. The video doesn't have notify when I'm pressing command+c, but you'll probably figure it out.