Hello @ColinL ,
The Reporting tab is also affected by the time frame you have set. So if you're only looking at a small time frame (such as 30 days), and you haven't sent that many emails during that time, then increasing the number of campaigns you see per page won't likely increase the number of campaigns displayed. If you increase the time frame, you're more likely to see more campaigns, and can adjust the number displayed per page as needed. To change the time frame, simply click on the dropdown menu at the top of the Reporting screen (see screencap below).
For example, when I set your time frame to 6 months, that increased the number of campaigns that could be viewed since they were then included in the data being displayed. The same with 9 months, 12 months, and custom ranges.