traffic shaping - How to limit bandwidth used by an IP in the penalty box in pfSense

We're trying to use the pfSense traffic shaping feature known as the Penalty Box. We are interested in limiting the bandwidth of a particular IP to 2%.

Note: There is a four-year-old bug in pfSense where you have the option to select other limiting options besides a percentage (e.g. kbit/s, bit/s, Mbit/s). But selecting any option other than % results in an error. Ideally I would have limited this one IP to 1 bit/s.

After the rules have been created/applied, the penalized IP is taking the majority of the link (e.g. 80%), rather than 2%:

How do I use the pfSense Penalty Box feature to limit the bandwidth of a particular IP?

The issue is that it consistently takes too much bandwidth, starving other (non-penalized) IP addresses.