A legendary story in the annals of diagnosing ICT issues is "The case of the 500-mile email":
https://www.ibiblio.org/harris/500milemail.html
in which the problem was that emails couldn't be sent further than around 500 miles.
Here's a bug in software related to CERN's LEP particle accelerator that was, in fact, literally caused by the phase of the moon:
http://beza1e1.tuxen.de/lore/moon_phases.html
This reminded me of the old somethingofthatilk.com comic about the blame chain in computing:
https://web.archive.org/web/20120712020833/http://www.somethingofthatilk.com/index.php?id=234