Do You Have a Name For

...when you go to look at someone's computer/device/app and it magically is working perfectly when they go to show you? Like when the person is "Oh sure NOW it works..." simply by your presence? (Sorta like how the car stops making The Noise when the mechanic is nearby)

I've always called it "I.T. Person Proximity Location Rectification" and was just wondering if we have a better name for the phenomenon

PEBCAK

That's more like when they show you it's not working after doing almost everything wrong which can possibly be wrong. Then you just show them the right way and suddenly it's "working" even though the only thing that changed is they just started click "save" instead of "cancel".

What OP is talking about is probably the user forgetting some detail about their actions immediately prior to the problem occurring and thereby being unable to reproduce the behavior, which is something anybody can do regardless of their technical knowledge.

How about LUCK? (Life's U - Unexpected C - Charms K - Keep spreading) suggested by...https://randomgenerate.io/mnemonic-generator

I've been told that computers have given their owners tons of grief... right up to the moment they considered calling me (I was their IT support)... then they worked correctly the rest of the day.

I always carried a Leatherman tool, and was unafraid to open a computer at a moment's notice. I ruled the computers by fear. ;-)

On the other hand... one of the people I supported did exactly the right things to her computer as I watched... and it didn't work... I recommended she avoid computers, and she's now a very happy motivational coach.