It might take a few seconds up to several minutes before the preparation of your Report has been completed. This depends on the amount of Consolidated Usage Records, and the amount days you'll have to prepare your report for. While the preparation of your report is running in the background, you may continue to use the system. However, until the preparation of the report has been completed, the report might not be showing any data. Only after preparation has been completed, the resulting data will be available for reporting via the Reports menu on the left side of the screen: