When building a Custom Insight in NXT report builder and selecting to compare the data to "same period previous year," drilling into the previous year renders a blank fly-out wheel. This is only an issue when the insight is built to display the data in table format. When you build it as a headline or bar graph, it functions correctly. Blackbaud says their vendor is aware and doesn't plan to fix it. But, if there are enough votes and they can demonstrate the need to their vendor, if might get fixed.