Tarnagh, that’s offically known as the Demo Effect. Sometimes it materializes by causing a malfunction when you are about to demo something. But even more prevalent occurrence is things working when you are trying to show someone that it doesn’t.
Oh, goodness, my dad used to be a system administrator, he worked with servers for some company and he had tons and tons of stories of how people would call him and some of his colleagues about problems with their computers and the moment they called everything started working perfectly well!
He still has the power over some electronic devices. Most of the time it's enough for him to just come close to something that doesn't work and it forgets its problems and runs without any issues
And things not working when you want to show them to other people?.. I think that's the curse of humanity :'D We are doomed to fail every time we demo anything...