My guess is when I press space it's triggering something like DropObject(); instead of InteractWithBird(); -- if it's a race condition between them your computer might just be hitting InteractWithBird(); faster than the rest of us, and we're all hitting DropObject(); . If it's a race condition it can seem kind of random like that.
Usually when I have something hard to reproduce like this I go back to the related code and talk out loud and read one line at a time to make sure the logic makes sense. They're some of the most annoying bugs to fix lol