I see that sometimes as well. Almost never on 120 volt applications - unless maybe if lightning was a factor.We see faults in sandy soil where the sand has turn to glass. At some point the current was high enough to accomplish that. That does not happen often, so the answer is, depends.
As current flows through soil around some of those faults, it dries up that soil making it a higher resistance which results in less current.
I once had a open circuit in an underground conductor and had a lot of trouble locating it. It was sandy soil and conditions had been very dry at the time. Dug two different holes in what I thought were most likely places for a fault to be according to my locator yet found nothing wrong in those spots. Ended up setting up sprinkler over the area and came back a few hours later - found the right spot very quickly. The locator finds where return current is leaking from the conductor via earth, soil was so dry there wasn't enough return current to get a good locate.
Not sure what model number is, but same manufacturer and very similar to this one, but probably about 30 years old. I didn't think I would find one on their site that looked so similar to what I have after that many years.What were you using as a locator? Just curious.