Count of record drops on the hour

Hello,

I am running a single node ELK cluster including filebeat. My main pipeline involves Filebeat > Logstash > Elastic and I'm running no log mutations or alterations in logstash. I am seeing periodic drops, approximately every 1 hour 15, of the count of records. My server has high throughput however it has plenty of memory and CPU power to cope. Are there any processes this could be linked too?

Any help or pointers diagnosing this?

Thanks.