You come across an issue in your system where caching for a service suddenly starts reducing and then ends totally.
If a caching service has dropped, it is most probably because the product service has changed to HTTPS (encrypted). And PeerApp does not cache for encrypted services.
PA does caching for any cacheable traffic except encrypted traffic. So make sure to check if your product service is encrypted. If it is, PeerApp won't cache for it.
In order to check the complete categorization of services being cached by the PA cache system, you can check Home | Statistics > HTTP Services > Total Downstream, and it will be shown there by service categories.