That's strange, your grep looks fine to me. Is it possible that you have configured nginx to use different log files for different locations (or maybe don't log at all)? Other than that, I don't have any good explanation.
Oops, I'm a dumby and hadn't had enough coffee yet. That file was just logging 301s, and the actual target was going elsewhere, which has an appropriate number of requests.
Overall pretty awesome, thank you!