In April of 2021, some changes were made to the DIY reports in CLASS. You can read bout the details of the changes, but this page will focus on "Additional Fields".
The reason behind making this particular change is that the DIY reports run much faster this way, it fact it was sometimes quite difficult, or not possible, to run a report for a large data set.
The change that was made is that all multi-select fields won't display data unless the report is specifically told to do so. An example of a multi-select field is problem type, where you can select as many options as you like.
This is a screenshot of a report with no data for a multi-select field (the problem type field has no data in it):
This is a screenshot of the "Additional Fields" feature:
And this is a screenshot of the report, after selecting 'Problem Type' in 'Additional Fields' and clicking load report again:
This feature doesn't work if you click 'Select All' in the 'Additional Fields' feature. You should only select the fields you need.