Same issue. It seems that after generating the reports (I'm checking after 7 days), some request_id / report_id provide empty instances so the final csv file is incomplete... With that, it's difficult to escalate the problem to Apple Support. Solutions? Wait for 31 days to request again the generation of ONE_TIME_SNAPSHOT reports and cross your fingers to get the data properly. If the aggregated metrics are valid for you, try to use a scraping strategy to extract them from the UI console.