The developer portal Sales reports can take up to 7 days to update with data on minutes of usage for Amazon Underground apps. The number of units sold however, updates on a more frequent interval. Therefore, you may see reports with number of units sold but 0 minutes engaged for up to 7 days. Reporting data on usage minutes will be refreshed once per day. Also, keep in mind that offline usage of Amazon Underground apps will be reported the next time the end user logs onto WiFi, or otherwise regains a data connection. Amazon pays the developer at the time the data is received, not when the data was collected.