Excatly. German speaker here, parent is correct. I looked for a description in English, I found this exchange on reddit which IMO describes it exactly:

"What never works exactly as it's supposed to?" "Opening YouTube videos on a PowerPoint" "It works fine until the actual presentation"

But it can also refer to a bug that usually happens not happening when you try to show the bug to someone else. E.g. having no TV reception for some reason and getting someone to look at it, but when they show up, the reception is perfect.