This has happened to me twice (EDIT: many times and I can replicate it) now. I'm working on a Raspberry Pi, looking for a file I already know exists and so I type this command:
sudo find / -iname 'firefox_binary.py'
The first time I type it, it runs without errors, but it doesn't find the file. However, when I run the same command only seconds later, it finds it.
It's the same command, run in the same terminal window, under the same path, on the same system, with the same file structure, with only a few seconds separating the first run from the second run. How is this result even possible?