Is there any reason why Netflow should disregard tiny transactions like these?
Yes, it is., process called Top Talker Optimization. With default set at 95% it stores flows which creates 95% portion of total bytes of incoming flows. This works just fine for most of our customers, however if you are interested in *VERY* small traffic, please increase the value to 100% in NetFlow Settings > Top Talker Optimization. Please note that storing 100% of incoming flows will affect required DB size and may also negatively impact charts and reports loading times.