Any value that you have a "Not Available" or "N/A" for in a report is a metric that can't be calculated, usually because some data required for the calculation is missing for all or part of the metric year used for the report date range. If the "Not Available" you are seeing is a blue, underlined hyperlink, you can click on it to see an explanation of why the value can't be calculated.
If you are viewing a report you generated on the Reporting tab or exported to Excel and "Not Available" isn't clickable, you can use the Metrics Summary chart on your property's Summary tab to see that same explanation.
In the Metrics Summary chart you can use the pencil icons to change the Period Ending Date to match the time period of the report. You can also change the metrics to reflect any you received a "Not Available" for. Then, once you have reproduced the "Not Available" metric, it will be clickable so you can see the explanation.
In this example, we want to learn why this property showed a "Not Available" for Direct GHG Emissions in a report ran for a year ending on July 31, 2019.
First, we're going to replace this Total Waste metric in the chart with the one we want to see: Direct GHG Emissions.
Next, we're going to update one of the time periods shown in that same chart to match the Period Ending Date we used in generating the report:
Now, when we check the updated chart, we see a "Not Available" hyperlink for that that metric, and when we click it, a pop-up box explains what data is missing and preventing the metric from being calculated.