I hate intermittent bugs.
You know, those ones that never always happen in a reproduceable manner. I had to test this bug that seems to happen 1 time in 20+ tries. Not to mention that I needed to do it from a cold boot, so it took 1-2 minutes per trial. Fortunately, I was able to automate it so I didn't need do anything except hit the power button every time it worked.
Twenty tries and I get nothing. So I send an email saying so, and that's just when the bug shows up. Then had to try a few different versions to figure out when it was introduced. But in the end it seemed nobody else could reproduce the bug (though someone could before).
Swapped development boards with someone and couldn't reproduce the bug after 50 tries... What a waste of a day...