Thanks. Just purchased this charger and will be returning the one I bought. Interestingly the description of the one I bought says it is PD compliant. But it appears that the cord they provided actually may have been the weak link.
Sorry to come late to the party, but I'd strongly advise going to Amazon now ordering one of these while the deal is still on, save some money and charge your batteries way, way faster. Return the other one, save half.
The Mini 4 batteries charging in the hub pull around 65W. You can fully charge a battery in less than an hour.