Google Analytics does not display data, but "Property Hit Volume" shows hits

How can Google Analytics report a "Property Hit Volume" of about oh, 10 or so on the last day, but report no data, no visitors, no transactions, no nothing?

I have a webshop that uses an external service for a affiliate program of a larger webshop.
The external service allows me to enter a Google Analytics Account ID (UA-xxxxxxx-x) and send a transaction to Google – I go from server to server. I have set up a separate property to prevent this transaction from confusing my conversion ratio, and this property shows nothing. However, the "Property Hit Volume" shows a constant hit volume. What could that do?

I suppose Google Analytics filters the hits out of something related to server-to-server tracking, and this property has never had a normal hit. I'm just not sure where to look.