As the title describes, I'm looking for a word or phrase that describes the phenomenon that a bug/error/etc. disappears when you want to show it to someone.
Example:
Your Internet connection does not work properly. You try everything to fix it, but it won't work.
You call an expert but then when you want to show the issue to them, your Internet connection seems to be fine. Obviously, once your expert left, your Internet connection is broken again. Bad luck.
So, what would you call it?
