I think you are running into this error:
It is fixed in 2.4.8. Can you upgrade?
To catch historical statistics, you will want to process your Apache logs instead of the faulty usage stats logs. See this page for details:
https://pkp.sfu.ca/wiki/index.php?title=PKP_Statistics_Framework#Processing_Log_Files
To ensure accurate statistics, you will need to clear the data from the faulty logs from the metrics table, by load_id (the filename). If you have a load from the usageEventLogs and from the Apache logs for the same day, you will be double-counting some statistics.