Naturally, I found the answer to this shortly after posting on StackOverflow. Turned out to be a syntax error in how I was formatting my templates. Here's what ended up working:

{% for entry in bills %}
<tr><td>
<form action="{% url 'select_software' bill_num=entry.Row page=1"><button type="submit">Select</button></form></td> [...]</tr>
{% endfor %}